* GB785754 (A)

Description: GB785754 (A) ? 1957-11-06

Improvements in and relating to drilling rigs

Description of GB785754 (A)

PATENT SPECIFICATION Inventor: BRIAN AITCHISON ENGLAND Date of filing Complete Specification June 1, 1955. Application Date June 1, 1954. 1 ' ' Complete Specification Published Nov6, 1957. Index at Acceptance: -Classes 80 ( 3), Z 6; and 85, A 1 D 2. International Classification: -E 21 b F 06 h. COMPLETE SPECIFICATION Improvements in and relating to Drilling Rigs We, HANDS-ENGLAND OILFIELDS EQUIP- MENT LIMITED, a British Company of New Icknield Way, Letchworth, Hertfordshire, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: - This invention relates to portable drilling rigs mounted on vehicles so that the rig can be quickly and easily moved from one site to another without the necessity of dismantling it. In the usual type of portable drilling rig of that kind the drill string is driven through a so-called " Kelly bar " of square or hexagonal cross section which passes through a guide cbush of similar cross section at the tail end of the vehicle The guide is rotated and rotates the Kelly bar which forms a part of the drill string As drilling proceeds, the lower end of the Kelly bar goes below ground level so tha when a new length of drill pipe is to be added to the string, the Kelly bar has to be withdrawn from the bore hole until the joint between it and the uppermost length of drill pipe is above the guide The uppermost pipe is then clamped in the guide while the Kelly bar is removed from the rig and a further length of drill pipe is added The drill string is then unclamped and lowered back into the

bore hole, the Kelly bar reinserted in the string, and the boring continued. Thus, much time and labour are wasted in raising and lowering the drill string when each additional length of drill pipe is added. Furthermore, raising the drill string withdraws the bit from the bottom of the bore hole and allows loose material from the sides of the hole to fall to the bottom In that case, the bit cannot be returned to the bottom of the hole and a further loss of time and labour results. In the portable drilling rig in accordance with the invention, the drill string is driven, not through the agency of a Kelly bar, but direct by a motor at or near the point of susIT pension of the drill string from a jib the pivot of which is arranged for movement fore-andaft of the vehicle in such a way that the point of suspension of the drill string moves substantially rectilinearly as the jib is raised and lowered. With this arrangement, a length of drill pipe can be added to the drill string simply by uncoupling the motor from the drill string, attaching a new length of pipe to the motor and raising the motor plus the new pipe by means of the linkage until the end of the new length of drill pipe is high enough to be coupled to the top end of the drill string, whereupon drilling can continue. Throughout the whole operation the bit remains at or near the bottom of the hole. Ideally, the linkage should be designed to move the motor accurately over a straight path along the axis of the guide It can, for example, be a straight line motion linkage of the ScottRussell type However, in practice, it is found that strictly rectilinear motion is not essential and, in fact, it is preferred to use a linkage based on a modified form of Scott-Russell straight line motion linkage which, although not quite so accurate, has other advantages. The raising and lowering of the motor is best effected by a hydraulic jack or ram which is preferably double acting so that a load additional to that due to the weight of the drill string can be applied to the drill bit by operating the jack in the lowered direction. The motor is also preferably driven hydraulically in which case it and the jack can be operated by one and the same pump which can be driven either from the power unit of the vehicle or from a separate power unit on the chassis, the latter being preferred The power unit of -the vehicle may be used also to drive a further pump for supplying drilling mud to the inside of the drill string for cooling the bit, and for carrying cuttings up to the surface Alternatively, an air compressor, serving a similar purpose to that of the mud pump, F,

785,754 No 16206/54. 785,754 may be fitted for use in areas where water is scarce or unobtainable. In order that the invention may be more clearly understood a portable drilling rig in accordance with it will now be described by way of example with reference to the accompanying drawings, in which:Figure 1 shows in simplified form a side elevation of a road vehicle carrying the rig in the travelling position; Figure 2 shows the rig prepared for use; Figure 3 shows the rig in the working position; Figure 4 is an end view of Figure 3; Figures 5-8 are diagrams illustrating the operation of the rig; Figure 9 is a diagram showing a conventional Scott-Russel linkage, and Figures 10 and 11 are diagrams illustrating modified forms of the linkage of Figure 9 which can be used to provide substantially straight line motion of the drill string. The vehicle shown in the drawings has a chassis 10 on which is mounted a jib 12 The jib is pivotally mounted at 13 on the upper ends of two posts 14 of a rigid frame 17, which are pivotally mounted on the chassis at 15 so as to be capable of swinging fore-and-aft of the vehicle. The chassis also carries a pair of fixed posts 16 at the upper ends of which are provided pivots 18 At the same height as the pivots 18, the posts 14 are provided with a pair of pivots The pivots are connected together by two pairs of links 21, 22 These links are of equal length and, at 23, are pivotally connected to each other and to links 24 the outer ends of which are connected to pivots 26 carried by the jib Where it does not interfere with the working of the jib, each pair of pivots may be replaced by a single shaft Indeed, it is preferred to replace the pivots 20 by such a shaft, in order to increase the rigidity of the frame 17. The chassis also carries a pair of hydraulic rams 27, the outer ends of which are connected to the shaft 26. At its outer end, the jib carries a motor unit 28 on horizontal trunnions 30 The motor unit, of itself, forms no part of the invention and need not be described in detail It can be assumed to consist of a pair of hydraulic motors mounted diametrically opposite each other and driving a common gear on a hollow spindle 32 suitably supported to withstand radial loads and up and down thrust loads The motors are supplied with oil from a pump on the chassis through pipes not shown in the drawxings. In the travelling position shown in Figure 1, the outer end of the jib is in its lowermost position so that the motor unit 28 rests in a cradle 34 at the rear end of the vehicle. When the rig is to be used, the rear end of the chassis is supported on jacks 36 and the outer end of the jib is raised slightly by means

of the rams 27 as shown in Figure 2 so that the motor unit comes clear of the cradle 34. The motor unit is then turned on its trunnions and a length of drill pipe 38 is attached to 70 the spindle 32 Thereupon, the jib is raised by the rams somewhat higher than the position shown in Figure 3 and is then lowered so that the drill pipe passes through a guide hole 40 in the base of the cradle 34 After attachment 75 of the drill bit to the pipe, the rig ready for drilling to start. For drilling, the jib is lowered while the drill pipe is rotated by the motor unit 28 The jib may be lowered by gravity but, it is pre 80 ferable that the rams 27 be double-acting so that they can serve to load the bit When the jib has been lowered to the vicinity of the cradle 34, the drive is stopped and the drill string is clamped in the guide hole 40 The 85 motor spindle 32 is then unfastened from the pipe 38 and disconnected therefrom so that the motor unit can be turned into the position shown in Figure 2 and a new length of pipe attached to it The jib is then raised until the 90 new length of pipe can be attached to the first and the drill string is unclamped Drilling then proceeds again until the jib is again at cradle level whereupon another new length of pipe is added to the string For clamping 95 the drill string, it is preferred to use an arrangement which is locked by the weight of the drill string itself Such an arrangement is shown in Figure 4. The guide hole 40 is slightly tapered The 100 bushing 42 (shown dotted) which during drillings, acts as packing between the drill string and the walls of the guide hole is removed, and in its place a pair of slips 44 are inserted. The slips 44 have se-rations on their inner 105 surfaces which can grip the drill string. Clamping is effected in the following manner: The drill string is raised slightly by means of the jib say one or two feet, and the bush 110 ing is removed The slips 44 are then inserted around the drill string and the jib is lowered. This causes the taper in the guide hole 40 to force the slips into contact with the drill string so that it is clamped securely, the ser 115 rations preventing any slip The motor spindle 32 can then be uncoupled from the drill string which remains clamped in the guide hole 40 under its own weight After a new length of pipe has been added, the jib is raised slightly, 120 the slips removed, the bushing replaced and drilling proceeds. It is to be noted that lengths of pipe can be added to the drill string without disturbing the pipe or pipes which are in the ground 125 During the drilling, drilling fluid is supplied to the bit through a flexible hose 42 running the length of the jib From the above, it

will be appreciated that immediately a new length of pipe has been add d to the drill 130 785,754 string, drilling fluid can be supplied to the bit so that at no time during actual drilling is the bit deprived of drilling fluid. It is, of course, essential that the drill string remain vertical which implies that the outer end of the jib travel over a substantially rectilinear path when being raised or lowered to the extent required by a pipe of normal length, say 10 ft This is ensured in the arrangement described above as can be seen from the diagrams of Figures 5-8 Of these Figures 5 and 6 show the essential parts (numbered as in Figures 1-4) in the positions shown in Figures 1 and 2; Figure 7 shows a typical drilling position; Figure 8 shows the jib at its highest position As will be seen by a comparison between the various diagrams, the pivot point 13 of the jib 12 on the posts 14 is moved laterally by the swinging of the posts about the pivot 15 so that the locus of the motor trunnions 30, instead of being a circular arc as it would be if the pivot 13 were fixed, becomes approximately rectilinear. The design characteristics of the arrangement shown in Figures 5-8 can be gathered from a comparative analysis of Figures 9-11. Figure 9 shows a conventional Scott-Russell straight line motion consisting of two links ADC and DF F is a fixed pivot; A is mounted for horizontal reciprocation; AD=DC= DF If A is reciprocated, C will be reciprocated rectilinearly at right angles to A Such a linkage could be used in an arrangement in accordance with the invention, AC being the jib with the motor unit mounted at C A system of this kind, however, introduces mechanical difficulties which are to be avoided. Figure 10 shows a modification of Figure 9 in which the point A, instead of being mounted for reciprocation is arranged for movement over a curved path determined by the oscillation of a link BA about the point B The longer the length of the link BA the more nearly rectilinear will be the path of the point C This arrangement is more satisfactory mechanically than that of Figure 9 but is still capable of improvement because whilst the link BA should be long to obtain as straight a path as possible for the point C, it is desired to keep the length BA to a minimum with a view to obtaining a small and compact linkage and yet a relatively long path for the point C. Figure 11 shows an elaboration of the arrangement shown in Figure 10 which consists in the addition of a parallel motion linkage shown in broken lines in which PQ is parallel to AC; DR is parallel to AP; PB AB -= The path of the point Q will then be PQ AC parallel to that of the point C and will be approximately rectilinear. The arrangement of Figure 11 has the merit of being mechanically sound and of providing 2 cr extensive movement of the point Q and forms the

basis of the design shown in Figures 1-8 A comparison between Figures 8 and 11 shows that the arrangements are identical except that the link DC of Figure 11 has been omitted as no longer being required 70 Among the most important advantages of the invention are that additions to the drill string can be made more quickly and that the bit remains at or near the bottom of the hole when lengthening the string The latter advan 75 tage is of particular importance when drilling in loose formations when removal of the bit allows the drilled holes to be filled up again. The mounting of the motor on the jib also 80 has the (advantage that the motor always remains above the drill string and is not subject to flooding when drill pipes are being disconnected. The jib and motor units need not neces 85 sarily be operated hydraulically but instead can be operated mechanically For instance, the rams 27 may be replaced by screw jacks and the motor 28 may be driven from the power unit through gearing 90

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* GB785755 (A)

Description: GB785755 (A) ? 1957-11-06

Improvements in or relating to electric telegraph equipment

Description of GB785755 (A)

PATENT SPECIFICATION Inventor: HARJOLD DODIMEAD GAITE Date of filing Complete Specification: May 13, 1955. Application Date: June 4, 1954 N Q Complete Specification Published: Nov6, 1957. Index at acceptance:-Class 40 ( 3), H 15 BZ(A; 134; D).

International Classification:-H 041. o 16563/54. COMPLETE SPECIFICATION Improvements in or relating to Eltctric Telegraph Equipment We, BRITISH TELECOMMUNICATIONS RESEARCH LIMITED, a British Company, of Taplow Court, Taplow, Buckinghamshire, do hereby declare the invention, for which we pray that a patent may be granted, to us, and the method by, which it is ito 'be performed) to be particularly, described in and by the following statement: - The present invention relates to electric telegraph equipment and' is more particularly concerned with the provision of a control unit suitable for controlling the operation of a plurality of tape readers and/or coders together with automatic message numbering equipment. Tape readers are well-known in the art and generally comprise equipment for driving punched tape step-by-step together with a set of five peckers which sense the holes in the tape and operate contacts when holes are encountered The expression coder " is intended to cover a unit by means of which a series of signals of a predetermined but adjustable nature can be transmitted over the line and this may conveniently take the form of a switching device employing a plurality of balls selectively arranged in radial lines on a disc adapted to be rotated step-lbyrstep by an electromagnet so as to bring the radial lines of balls successively in register with a corresponding set of contact fingers Such a switching device is disclosed in' our Specification No 747,188, Alternatively use may 'be made 'of a perforated disc type of switch such as shown in our Specification No '697,913. The object of the present invention is to provide a control unit whereby the desired operations may be carried out automatically, including the changeover from one tape reader to another, the automatic insertion' of the message number and the provision of the call sign. Facilities are also provided whereby a test message or a routine message may be transmitted in response to the throwing of a test key or alternatively a keyboard may be connected up to enable a suitable message to be keyed,. According to the invention in a control arrangement for electric telegraph equipment for controlling automatic sending from a plurality of tape readers, the different readers are connected up over the wipers, of an electromagnetically-operated step-by-step switch which is automatically advanced through positions to which no tape readers are connected but in which 'control of transmission is effected. The invention will be more fully understood from the following description of a preferred form which should 'be taken in conjunction

with Fig 1 of the drawing accompanying the provisional specification and the accompanying drawings which will be referred to as Figs. 2-4, Of these Fig 1 shows a known type of uniselector in sufficient detail to permit its method' of operation to 'be appreciated and also shows the manner in which its banks would be wired in association with the grouping of the pins' on its base by which it is plugged into a suitable socket, Fig 2, shows the interconnection between the banks A-E of the uniselector, that is, to says those banks over which the actual control of the signals, is effected and allso indicates the various bases or sockets into which t 1 he tape readers, coders and keyboard would be plugged Figs 3 and 4, when fitted together with, Fig 3 on the left represent a circuit diagram showing how the connections to the control bank F of the uniselector serve to produce the desired, operation in connection with the other units and the group of control relays It should be mentioned that in Fig 2 the connections from the various sockets which terminate in arrow heads extend to the corresponding points; on Figs 3 and, 4 where they are marked with a similar notation. Considering first Fig 1, this shows a known construction, of uniselector which is operated by an electromagnet 13, provided with an armature 14 carrying a pawl 15 engaging with a ratchet wheel 16 The switch is, provided with 12 positions, and the wipers which engage with the various bank contacts each com785,755 prise a spider with three equally-spaced arms such as 17 and the bank contacts 18 occupy of arc A further position W serves to permit the necessary connections to be made to the wipers by a slip ring arrangement as is well understood 'Stepping of the wipers takes place on energisation of the electromagnet and in the form shown the switch is assumed to have six banks or levels A-F The table in Fig 1 indicates the wiring of the bank contacts to the contacts in the base on which the switch is mounted and the significance of the wiring arrangements will be appreciated as the description proceeds. It will be seen that the showing of Fig 2 does not include the control bank F of the uniselector and this is dealt with in Fig 3 It should be mentioned also that the base SKV in which is inserted the plug 'PLV from the feed wipers of the uniselector extends to a distributor 'PLB for instance of the electronic type as described, in detail in our Specification No 12204/54 (Serial No 765,227), whereby the potentials selectively applied simultaneously to the signalling leads are given te appropriate time sequence. Considering now the circuit diagram of Figs. 3 and 4, this includes a number of electromagnets which are used for stepping the various pieces of equipment such as coders and tape readers which may be associated with the control unit The magnet N

serves to step the coder which controls the transmission of the serial number of the message, this stepping operation taking place at the end of the message in order to add one unit to the number Magnet Y serves to step the Y tape reader magnet Z steps the Z tape reader, magnet T steps the test coder by means of which a test message can be repeatedly transmitted for as long as is desired, magnet Q steps the routine coder, magnet U steps the uniselector and magnet P steps the preamble coder for generating the call sign and effecting the proper setting of the receiving equipment to receive the message. As regards the operation of the distributor, it should be explained that this is set in operation by the connection of earth to terminal V 7, Fig 4, and this applies pulses to terminal V 12 at the appropriate transmission speed The connection of earth to terminal V 1 l, Fig 3: results in the transmission of a continuous mark signal and similarly the connection of positive from terminal V 10 to terminal V 9 Fig 4, ensures the transmission of a continuous space signal. Considering now the operation of itransmitting messages under the control of tapes in the Y and Z tape readers, plugged into the double sockets 'SKYA and SKYB and SKZA and SKZB respectively It will be assumed that the equipment is in the position shown with the uniselector in its home position which is position 2 In these circumstances a small current flows through magnet N which is not enough to cause its operation but prevents the capacitors Cl C 2 and C 3 from being charged to any appreciable extent Moreover, as may be seen from Fig 2, in this position earth is 70 connected to the contacts in banks A-E and this earth is extended to the distributor to produce a letter shift signal. Assuming that a tape has now been properly placed in the Y tape reader, the tape 75 sensing contacts TSY, Fig 3 will be closed and a circuit will then be completed from earth over contacts Fl and TSY, relay A resistor R 8 and relay F to positive Relay F is somewhat slow to operate owing to the large 80 value capacitor C 7 shunting its winding but relay A operates immediately and at contacts Al prepares a circuit for relay E, at contacts A 2 completes a locking circuit for itself independent of contacts Fl, at contacts A 3, Fig 85 4, removes the short-circuit from the tight tape contacts TTY so as to render these contacts effective, and at contacts A 4 prepares a stepping circuit for magnet Y of the Y tape reader Relay F on operating after its slow 90 period, at contacts Fl opens the initial circuit for relay A, at contacts F 2 opens a point in the energising circuit for relay B, at contacts F 3 opens a point in the energising circuit for relay J and at contacts F 4 extends earth over 95 contacts G 3, switch SWD 2, contacts B 3 and TTY to terminal V 7. The distributor is accordingly set in operation and a driving pulse is

shortly applied to terminal V 12 whence it is extended; over con 100 tacts -E 3 and H 1 to operate magnet U and cause the uniselector to step to position 3. Wiper F now opens the circuit of magnet N and permits capacitors Cl, C 2 and C 3 to start to charge As shown in Fig 2, bank contacts 105 A-E in position 3 are wired in the same way as those in position 2 so that the equivalent of a letter shift signal is again transmitted The distributor continues to operate and the next pulse over terminal V 12 steps the uniselector 110 to position 4 Here again banks A-E are connected to earth but over bank F earth is connected to terminal V 1 i to ensure the transmission of a continuous mark signal and the uniselector then stops to position 5 The 115 wiring in this position is similar and consequently a mark signal is again transmitted. The next pulse from the distributor advances the uniselector to position 6 in which banks A-E are wired for the preamble coder 120 by way of socket SKP as shown in Fig 2. This initial period of 450 milliseconds without signalling allows the motor of the receiver to approach its normal running speed from the position of rest and thus to be in synchronism 125 with, the transmitter. In position 6 of the uniselector a circuit is completed over the F wiper, Fig 3, and contacts PA for relay H which accordingly operates and at contacts H 1 connects up magnet 130 785,755 q 85,755 P in place of magnet U so that at the end of the first character when the driving pulse is received from the distributor, magnet P of the preamble coder is operated The various characters of the call sign are thus transmitted in turns the coder being advanced one step after each character and during the transmission of the last character, during which, a figure shift is transmitted, the switching member PA is changed over mechanically so as to release relay H and prepare an alternative circuit for it, Relay H therefore again connects up magnet U which is operated by the next drive pulse from the distributor to advance the uniselector to position 7. Positions 7, 8 and; 9 of banks A-E are wired to the peckers of the serial number coder connected to socket SKN, Fig, 2, which therefore controls the transmission of the three digits of the serial number, the uniselector being advanced one step after each digit. When it arrives in position 10, a circuit is again completed for relay H which therefore again connects up the magnet P' of the preamble coder It will be seen from Fig, 2 that positions '6 and'10 of bands A- E are wired together The preamble coder is therefore operated further and now serves to transmit carriage release and line feed signals to effect the correct positioning of the platen or printing head of the receiving printer in preparation for the message proper When this

transmission is completed, contacts PA are restored to their original position as shown in Fig 3 and relay H therefore releases and again connects up the magnet U of the uniselector, This is operated 'by the next drive pulse from the distributor to advance the uniselector to position 1 1. In this position a circuit is completed over bank F and contacts Al for relay 'E which accordingly operates and at contacts El, Fig. 4, opens a point in the holding circuit for relays D and' 'G, at contacts E 2 removes one of the connections for applying earth to the distributor hold lead over terminal V 7 and at contacts E 3 connects up the magnet Y of the Y tape reader The peckers 'of this reader are now effective over banks A-E, position 11, and the transmission of the message on the tape therein now takes place The tape is advanced one step after each character by magnet Y which is energised 'by successive pulses from the distributor applied to terminal V 12. At the end of the transmission when the tape has run out, the tape sensing contacts TSY are opened and interrupt the circuit 'of relays A and F Relay A thereupon releases but before relay F has released,, a further circuit is completed for it over wiper F in position 11, back contacts Al, rectifier 'MR 1 and resistor R 7 Relay E is released 'by the opening of contacts Al and thereupon at contacts E 3 transfers the pulse circuit back to magnet U. Accordingly when the next pulse is received the uniselector is advanced to position 12 In this position a similar circuit is completed for relay F over back contacts Bl and the connections therefore remain the same and 70 the uniselector is advanced to position 1 In this position relay F is maintained over back contacts J 1 and hence the uniselector is advanced to position 2 In this position there is no longer any circuit for relay F and it re 75 leases, thereby at contacts F 4 removing earth from the distributor hold lead and, thus arresting its operation, Moreover capacitors 'C 1, C 2, and, 'C 3, are now able to discharge through magnet N which, therefore steps the serial 80 number coder so as to add one unit to constitute the number next to be transmitted. The equipment has therefore now been restored to normal and unless there is a tape in reader Z or the test message or routine coders 85 are brought into operation, no further action will tale place. If however, thre is already a tape in the Z tape reader, contacts T'SZ will be closed and on the closure of contacts F 2 when relay 90 F releases, a circuit is completed from earlth over contacts J 2,, A 2, TSZ and F 2 for relays B and 'F in series Relay B operates immediately and produces effects in all respects similar to those produced 'by relay A but in 95 relation to the Z tape reader so that transmission takes place under the control of this' reader in, the manner just

described While the message represented by the tape in the Z reader is being transmitted, the Y tape reader 100 can be provided with a further length of punched tape Similarly the Z reader may be recharged while sending takes place under the control of the Y reader and on this basis sending may take place continuously as long 105 as, the traffic persists. If it is desired to transmit a message without a serial number, key 'SWA is operated and this 'by closing contacts SW Al maintains a circuit through magnet N and prevents 110 the charging of capacitors l Cl, G 2 and 'C 3 and thus the subsequent stepping of the serial number coder Moreover, these 'contacts remove the short-circuit from the gas; discharge tube L'Pl and this strikes to furnish a visual 115 indication that the numbering operation has been cut out In addition contacts SWA 2 ensure that earth is applied to terminal V 11 in positions 7, 8 and, 9 of the uniselector and hence that the output is held at mark during 120 this period This method' of operation may be desirable if for some reason the tape has been wrongly inserted and, needs to be removed for readjustment If it is desired to transmit a test message, 125 which would ordinarily be done at a time when there was no tape in either of the tape readers, the key SWB is operated This thereupon completes, a circuit from earth over zcontacts 'Gl, 'D 1 and F 3 ' for relay J in series with 130 4 z 785,755 relay F Relay J on operating, at contacts J 1 prepares a circuit for relay E, at contacts J 2 opens the initial circuit for relays A and B, at contacts J 3 completes a 'locking circuit for itself and at contacts J 4 prepares a circuit for the magnet T of the test coder Relay F oper-' ates as before after a short delay and by applying earth to terminal' V 7 starts the operation of the distributor and hence the stepping of the uniselector Relay F also at contacts F 3 completes a holding circuit for relay J to ensure a complete cycle of the uniselector independently of switch SWB It will be seen that the effect of relay J is generally similar to tha, of relays A and, B except that in this case the uniselector comes to rest in position 1 and the test message is sent out under the control of the test coder plugged into sock-et SKT, Fig 2 I When it is desired to stop sending the test message, which will otherwise continue indefinitely, switch SWIB is restored and the message is then completed under the control of off-normal contacts TA, Fig 3, on the test coder, which restore to the position shown when the message is completed This releases relay I and hence relay E and permits the uniselector to step to its normal position 2 Relay F is then released and by removing earth from the distributor hold lead, terminates the operation of this equipment. If operation is, to take place under the control of the routine coder, which serves for the sending of short messages which are frequently

used, switch SWC is momentarily operated and a circuit is then completed from earth by way of contacts G 3, switch SWD 2, contacts B 3, A 3 (, F 4, SWC, relay D, contacts F 3, relay J, resistor Rll, relay F to positive. Relays D and IJ both operate in this circuit and relay J produces substantially the same effects as before Relay D at contacts D 1 disconnects switches SW-B and SWF at contacts f D 2 completes a locking circuit for itself, at contacts D 3 opens a point in the initial circuit for relay 'G and at contacts D 4 connects up the magnet Q of the routine coder As before the uniselector steps round to position 1 and transmission is now controlled by the routing coder which is plugged into socket SKQ Fig 2 Contacts QA are operated as soon as this coder steps from its normal position and serve to maintain the circuit of relay D after it is opened at contacts El When the routine test message has been transmitted, contacts QA are again opened and relays D, L, E and F are released and the uniselector is stepped on to position 2. If it is desired to stop a transmission which is in progress from either of the tape readers, key SW'D, is operated This thereupon at contacts SWD 2 Fig 4, removes the earth from the distributor hold lead by way, of terminal V 7 and this arrests the operation of the distributor Moreover, switch SWD 2 in its alternative position completes a locking circuit for relay B if this relay is the one that has been operated, while if on the other hand relay A has been operated corresponding to tape reader Y, a locking circuit for this relay is 70 completed over contacts SWD 1, Fig 3, of the switch As soon as the switch is restored to normal, sending is resumed. Switch SWE Fig 4, may be operated when it is desired to send a supervisory space signal 75 and its effect is to connect positive from terminal V 10 to terminal V 9 and as previously pointed out, this produces circuit changes in the distributor which ensure that a continuous space signal shall be transmitted 80 The purpose of switch SWF, Fig 3, is to enable the call sign and message number to be transmitted when a message is sent from a common transmitter to several channels at once It will be seen that switch SWF pro 85 duces the same effect as switch SWB except that its operation is only momentary Relay j is operated as before and is locked up dependent on contacts El Hence no message is sent when the uniselector steps round to posi 90 tion 1 since relay E operates momentarily and; releases relay T and the result is the transmission of the call sign and message number only. If the keyboard is to be brought into use, 95 the switch MA, Fig 4 is operated and a circult is then completed from earth over contacts D 3, switch MA, relay G, contacts F 3 ', relay J, resistor Ri 1 relay F to

positive The operation of relays F and J produce the same 100 results as previously and relay G at contacts G 1 opens the circuit for relay J over switch SWB, at contacts G 2 completes a temporary locking circuit for itself to ensure a full cycle of the uniselector in case switch MA should 105 be restored prematurely, at contacts G 3 prepares a circuit for applying pulses to terminal V 7 and at contacts G 4 connects up the key release magnet of the keyboard so that this will be operated from the distributor This 110 magnet is not shown in Fig 4 but it will be connected, between points M 5 and M 14 when the keyboard is plugged into socket SKM, Fig 2 It will be appreciated that for the call sign and serial number transmissions earth is 115 provided over contacts E 2 but this connection is removed when relay E operates on the uniselector reaching position 1 and also relays F, J and G are then solely dependent on the keyboard switch MA 120 It should be explained that negative is normally connected from the distributor through a resistor to terminal V 15 Fig 4, and consequently capacitor CM is charged The contacts MB are changed over on each key opera 125 tion and, the capacitor then discharges over contacts G 3, switch SWD 2, contacts B 3, A 3 and F 4 to apply a negative pulse to terminal V 7 to produce the same effect as the normal earth connection but only for a predetermined 130 sion of an unwanted character if a waiting tape is in position The pecker contacts associatedl with position 1 are all open at rest and if J 1 were connected in the same way as Al and Bi, at the end of a coder or keyboard 70 message the output would be pulled to mark halfway through a character when 71 releases. Therefore rectifier MR-1 is used to isolate the mark hold circuit from J 1 and an " an-blanlk" character is sent when the uniselector wipers 75 reach position 1. It will be appreciated that though in most cases there would be no advantage in employing more than two tape readers, this could if required readily be done by suitable extension 80 of the circuits shown in Figs 3 and 4.

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* GB785756 (A)

Description: GB785756 (A) ? 1957-11-06

Improvements relating to tractor vehicles with trailers

Description of GB785756 (A)

PATENT SPECIFICATION Inventor: 'WILLIAM WHARTON Date of filing Complete Specification: Sept 16, 1955. Application Date: June 17, 1954. No 17785/54. Complete Specification Published: Nov 6, 1957. Index at acceptance:-Class 103 ( 5), B 2 G. International Classification:-B 61 g. COMPLETE SPECI'FICATION Improvements relating to Tractor Vehicles with Trailers We, WHARTON ENGINEERS (ELSTREE) LIMITED, of Watford 'Road, Eilstree, i Hertfordshire, a British Company, do hereby declare the invention, for which we pray that a patent may be granted, to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to tractor vehicles with trailers. The reaction to the turning effort applied to the wheels of a tractor, with a trailer attached, tends to rotate the tractor bodily in a sense opposite to the direction of rotation of the wheels, Consequently there is a tendency, regardless of whether the front, back or both wheels are driven, for the front wheels of the tractor to be lifted off the ground The weight of the tractor ordinarily counteracts his reaction until it is balanced by it, but nevertheless the front wheels exert little or no pressure on the ground and therefore cannot usefully be used for driving or steering the tractor. The object of this invention is to counteract this disadvantage and to this end according to this invention there is provided in com bination a tractor vehicle and a trailer with interposed draw bar connecting means, said combination having a draw bar connector member on the tractor formed so as to define a chamber for a pressure transferring hydraulic fluid medium; a piston element adapted, to be connected to the draw bar from the trailer and arranged within said chamber so as to be capable of exerting on the fluid medium therein pressure directly proportionail to the force of the draw bar pull; means

controlled by the pressure exerted' on' the fluid medium in' said chamber for exerting a downward thrust from the trailer to the tractor and thus counteracting the tendency of the latter whilst towing the trailer, to rotate about its back axle, said means' including a valve mounted on the tractor and forming an element in a closed circuit for pressure transferring hydraulic fluid medium independent of said lPrice 3 s 6 d l chamber, said valve having a control element which is subject to the pressure exerted on the fluid medium in said chamber and being adapted to cause a downward thrust on the tractor from the trailer which varies with the draw bar pull. Preferred features of this invention will become apparent from the following 'description of two embodiments,thereof, and the appended claims: In' the accompanying drawings: Figure 1 illustrates a tractor-trailer combination to which the present invention has been applied, Figure 2 is a diagrammatic lay out, on a larger scale, of the parts of the transfer means provided in the tractor-trailer combination illustrated in' Figure 1, Figure 3 illustrates another tractor-trailer combination to which the present invention has been applied, and Figures 4 A, 48, 40 and 4 D show, on a larger scale, details of the tractor-trailer connection of the combination illustrated in Figure 3, 4 A 4 being a plan view, Figure 4 B a side elevation, lFigure 4 C 'a rear elevation and Figure 4 D a section on the line D-D of Figure 4 C. In Figure 1 there is shown a tractor A in combination with a four wheel trailer B The trailer is connected to the tractor by means of ia draw 'bar 1 L provided at each end with the suitable universal joints. The trailer B includes at its, forward end an, upstanding element 2 to which is pivotally connected one end of a rod' 3; carrying at its other end a ram which is disposed in a hydraulic cylinder 4 The 'cylinder is connected to the tractor chassis, the ram, cylinder and rod being as a whole forwardly and; downwardly inclined from the front of the trailer to a point on the rear en,& of the tractor chassis. The tractor 'chassis frame is provided at each side with a rearwardly and downwardly extending member 5, the two members being rigidly connected by a cross bar 6 The draw bar connection is through the inter7853756 mediary of this cross bar 6 as will now be explained with particular reference to Figure 2. The draw bar 1 is connected by means of a vertical pin 10 to a member 11 which embraces the cross bar 6 and is 'capable of a small backward and forward sliding movement with respect thereto, the member 11 having rigidly secured therein a rearwardly extending pin 12 carrying a piston 13 This piston is slidably disposed in a chamber 14 in the cross bar 6 which chamber is filled with hydraulic fluid on the side of the piston 13 opposite to the pin 12.

The chamber 14 is connected by a pipe 15 to a chamber 116 at one end of a control valve, indicated generally by the reference numeral 17 An inlet 18 of this control valve is connected by a pipe 19 to a pump 20, and an outlet 21 is connected, by a pipe 22 to a tank 23 for hydraulic fluid, the tank being connected by a pipe 24 to the pump 20. Another outlet 25 of the control valve 17 is connected by a pipe 26 with the cylinder 4, a branch 26 x in the pipe 26 communicating with the fluid chamber of an accumulator 27 containing hydraulic fluid' and' compressed air separated by a piston or diaphragm The outlet 25 ' is in permanent communication with a chamber 28 at the end of the control valve remote from the chamber 16. The piston 29 of the control valve 17 has two spaced annular grooves 30 and 31 in the periphery thereof It will be understood that this whole system is normally filled with hydraulic fluid, and that the parts thereof may be mounted in any suitable manner on the tractor. During steady towing of the trailer by the tractor without variation of tractive effort the piston 29 occupies the position shown in Figure 2 The pump 20, which is driven by any suitable means from the engine of the tractor, operates continuously to pump hydraulic fluid, passing to it from the tank 23 to the inlet 18 of the control valve, into the groove 30 in the piston 29 and so to the outlet 21, into the pipe 22 and back to the tank 23 The fluid pressure in the accumulator 27 acting in the chamber 2 '8 is balanced by the fluid pressure in tthe chamber 14, acting in the chamber 16 and the piston 29 remains stationary The fluid pressure in the accumulator 27 also acts on the piston of the ram in the cylinder 4 which counteracts the tendency of the tractor body to lift or rotate about the back axle thereof. An increase on the draw bar pull causes the piston 13 to be moved rearwardly in chamber 14 forcing hydraulic fluid therefrom into the pipe 15 and so into the chamber 16 of the conterol valve 17 The piston 291 is thus caused to move to the left as seen in Figure 2 This isolates, the inlet 18 from the outlet 21, but puts it into communication through the groove 30 with the outlet 25 so that hydraulic fluid is then pumped along the pipe 26 X to the accumulator 27 in which, together with the ram cylinder 4 the pressure is increased This increases the force counteracting the tendency of the tractor body to lift or rotate about the 70 back axle thereof. When this increased force reaches a value appropriate to the increased draw bar pull, pressure in the pipes 26, 26 X causes fluid to flow back to the chamber 28 and the piston 75 29 is moved to the right again to its initial position, thus putting the inlet 18 into communication with the outlet 21 again. The force on the piston 12 and consequently the fluid pressures in the chambers 14 and 16 80 is due partly to the horizontal component

exerted by the piston of the ram in the cylinder 4 and partly to the draft of the trailer The former part is always proportional to but less than the pressure in the cylinder 4 and the accumu 85 lator 27, which pressure is effective in the chamber 28 of the control valve, so that opposing the effect of the draft of the trailer there is always a force proportional to the pressure in the cylinder 4 and the accumulator 27 tend 90 ing to move the piston 29 to the right. During the movements of the piston 29 in either direction there is a moment when the inlet 18 is isolated from both outlets 21, 25 and a relief valve 32 is provided in a pipe 95 33 communicating the pipe 19 with the pipe 22. Occasions may arise causing a sudden movement of the ram in the cylinder 4 resulting in a momentary excessive increase in the pres 100 sure in the hydraulic system A second relief valve 34 is arranged in a pipe 35 connecting the ram cylinder 4 with the pipe 22. For the main movements of the ram which occur during normal towing of the trailer 105 over undulating ground, the accumulator 27 acts as a buffer or spring. A decrease in draw bar pull will allow the pressure of the fluid in the accumulator 27 and the chamber 2 8 to move the piston 29 110 further to the right forcing fluid out of the chamber 16 into the chamber 14 This puts the 'outlet 25 of the control valve into communication with the outlet 21 through the groove 31 Fluid is let out of the accumulator 115 27, in which and in the ram cylinder 4 the pressure decreases When this pressure is appropriate to the reduced draw bar pull the piston 29 returns to its initial position. In Figure 3 there is shown a tractor A in 120 combination with a two-wheel trailer vehicle C, the latter connected to the tractor by a single draw bar member 40 disposed centrally of the rear axle of the tractor. More specifically, as is clear from Figures 125 4 A to 4 D, a cross bar 41 is rotatably mounted in and extends between, the side members 42 of the tractor ichassis, the ends of the cross bar being of circular cross section but the central part thereof being of rectangular cross section 130 785,756 7 r 85 ,7 '5 '6 3 and also upwardly bowed (See Figure 4 C) The connector 43 for the draw bar member 40 is pivotally connected to the centre of the cross bar 41 by, a horizontal pin 44 lying on the longitudinal axis of the tractor The connector also includes a vertical pivot pin at right angles to the pin 44, the arrangement being such that the connector as a whole forms a universal coupling between the side members 42 and the draw bar member 40. As is shown in Figure 4 D the connector 43 is capable of a small backward and forward sliding movement on the pin 44 and carries is a

piston 45 ' which is slidably disposed in a chamber 46 which surrounds the pin 44 in' the cross bar 41 and is filled with hydraulic fluid. Rigidly mounted on each end of the cross bar 41 is an upstanding arm 47 to the upper end of which is pivotally connected a rod 48carrying 'at its other end, a ram which is disposed in a hydraulic cylinder 49 The two cylinders are pivotally connected to brackets secured to the side members 42 of the chassis frame. A control valve 17, pump 20, tank 23, accumulator 27 with connecting pipes and relief valves are mounted on the tractor as described above with reference to Figure 1 The pipe 15 ' connects the control valve with the chamber 46, and the pipe 2 '6 connects the control valve with the cylinders 418, The operation of the hydraulic system will readily be understood from that previously given in connection with Figure 1. The chambers 14 an'd 4,6 and the chambers 16 'and 218 of the control valve may be replaced by hermetically sealed flexible capsules containing fluid, 'It will also be understood that one tractor may be adapted for towing four or two wheel trailers.

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* GB785757 (A)

Description: GB785757 (A) ? 1957-11-06

Improvements in scraper devices for use with rollers

Description of GB785757 (A)

COMPLETE SPECIFICATION Improvements in Scraper Devices for use with Rollers We, OSCAR LEGG LIMITED, a British Company and WILLIAM HENRY GILLINGS, a British Subject, both of 117 Goswell Terrace, Goswell Road, London, E.C.1, do hereby declare the invention for which we pray that a patent

may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to devices for use in association with rollers to remove material which has become adherent to the roller during the operation of the latter. IFor example, in conveyers for handling to bacco, the conveyor may comprise a belt passing over upper and lower rollers in which case particles of tobacco are liable to adhere to the rollers land build up a hard crust of tobacco thereon. It has been found that the usual doctor blade is inadequate to remove the tobacco in such circumstances because much of the mater- ial removed is re-conveyed back to the rollers, and the present invention has for its object to provide an improved form of device for removing tobacco or other material which may have become adherent to la roller. According to the present invention there is provided a device for removing material from a roller, comprising a trough-shaped member in the form of a part-circular section sleeve, e.g. a tube with part of is wall cut away, an axial edge of the sleeve or tube being arranged to engage the roller to, scrape deposited material from such roller and pass the same into the trough, and means for taking away the material collected in the trough in the form of an Archimedian feed screw rotatably mounted within the trough. In order to explain the invention more completely, one embodiment thereof will now be described iby way of example with reference to the drawings accompanying the Provisional Specification as applied to the removal of tobacco from the lower roller of an ascending belt conveyor or for feeding tobacco from a hopper. In the drawings, Figure 1 shows an outside end elevation of the apparatus, Figure 2 shows a section on the line II-II in Figure 1, and Figure 3 shows a section on the line III III in Figure 2. In the construction shown in the drawings, the hopper is indicated at 1, the lower roller at 2 and the belt conveyor, which passes around the roller 2, is shown at 3. The roller 2 is supported on trunnions 4 rotatably mounted in bearings 5 carried in side frame members 6. Bearings 5 are shown in Figure 2 but are omitted from Figure 3 for the sake of clarity. Mounted parallel with the roller 2 is the scraper element in the form of a tube 7 which is out away along the greater part of its length between its ends as shown at 8, the tube being mounted with the lower edge 9 of its cut-away potion bevelled and bearing against the roller 2.

Disposed within the tube 7 is a shaft 10 carrying an endless feed screw 11, e.g. similar to an Archimedian screw. The tube 7 is fixed to discs 12 one at each end of the tube by means of which discs the tube is fixed in! position. in order to move the tube bodily to adjust the position of its scraper edge 9 relatively to the surface of the roller 2, the tube supporting discs 12 are attached to fixed supporting plates 13 by screws 14 passing through arcuate slots 15 in the discs. The shaft 10 is supported at its right-hand end (Figure 2) in a bearing 16 in the tube 7 and at its left-hand end extends through a closure disc 17 in the tube 7, the left-hand end of the shaft 10 carrying a pulley 18 by means of which it is driven through a belt 19 from a pulley 20 on the trunnion 4. A suitable bearing for the shaft is also provided in the left hand end of the tube. With this construction, as the roller 2 resolves, any tobacco which tmiay have fallen on to its surface is scraped off iby the scraper edge 9 of the tube 7 and falls into the trough formed by the remainder of the tube whence it is removed by the rotating endless screw 11. At the right-hand end of the tube 173 (Figure 2), the latter lis cut away as indicated at 21 to form an opening through which the tobacco removed by the endless screw 11 is discharged. in conveyors of the form illustrated in the drawing, tobacco may also cling to the upper roller (not shown). In order to remove said tobacco from the upper roller, an ordinary doctor blade may be used since the tobacco thus removed falls down to the bottom roller and is scraped off into the tube ;7 whence it is discharged by the endless screw 11. The scraper edge 9 of the tube m'ay be shaped to the contour of the roller, for example if the roller is "crowned" or " cambered " the scraper edge will be correspondingly shaped. Although the invention has been particu- larly described as applied to the removing of tobacco from a conveyor or roller, the same construction can equally well be applied to the removal of tobacco or other material or substances from rollers used for other purposes. What we claim is: - 1. A device for removing material from a roller, comprising a trough-shaped member in the form of a part-circular section sleeve, e.g. a tube with part of its wall cut away, an axial edge of the sleeve or tube being arranged to engage the roller to scrape deposited material from such roller and pass the same into the trough, and means for caking away the material collected in the trough in the form of an Archimed,ian feed screw rotatably mounted with the trough. 2. A device according to claim 1, including means supporting the trough-shaped member adjustably about an axis extending axially of such member to adjust the scraping edge relatively ito the periphery

of the roller. 3. A device for removing material from a roller, substantially as hereinbefore described with reference to the drawings accompanying the Provisional Specification. PROVISIONAL SPECIFICATION Improvements in Scraper Devices for use with Rollers We, OSCAR LEGG LIMITED, a British Company and WILLIAM HENRY GILLINGS, a British Subject, both of 17, Goswell Terrace, Goswell Road, London, E.C.1, do hereby declare this invention to be described in the following statement: This invention relates to scraper devices for use in association with rollers to remove material which has become adherent to the roller during the operation of the latter. For example, in conveyors for handling tobacco, the conveyor may comprise a belt passing over upper and lower rollers in. which case particles of tobacco are liable to adhere to the rollers and build up a hard crust of tobacco thereon. It has been found that the usual doctor blade is inadequate to remove the tobacco in such circumstances and the present invention has for its object to provide an improved form of device for removing tobacco or other material which may have Ibecome adherent to a roller. According to the present invention the scraper is in the form of a trough-shaped element extending along the roller with one edge bearing against the roller surface and facing in the direction opposite to that in which the roller is rotated so that material scraped from the roller passes into the trough, while within the trough there are disposed means for removing the material collected therein. Preferably the trough-shaped member is in the form of a tube with part of its wall cut away and the means for taking away the material collected in the trough is in the form of an endless screw or spiral rotatably moun ted within the trough. In order to explain the invention more completely, one embodiment thereof will now be described by way of example with reference to the accompanying drawings as applied to the removal of tobacco from the lower roller of an ascending belt conveyor or for feeding tobacco from a hopper. in the drawings, Figure 1 shows an outside end elevation of the apparatus, Figure 2 shows a section on the line II-II in Figure 1 and, Figure 3 shows a section on the line IIIill in 'Figure 2. in the construction shown in the drawings, the hopper is indicated at 1, the lower roller at 2 and the belt conveyor, which passes around the roller 2, is shown at 3.

The roller 2 is supported on trunnions 4 rotatably mounted in bearings 5 carried in side frame members 6. Bearings 5 are shown in Figure 2 but are omitted from Figure 3 for the sake of clarity. Mounted parallel with the roller 2 is the scraper element lin the form of a tube 7 which is cut away along the greater part of its length between its ends as shown at 8, the tube being mounted with the lower edge 9 of its cut-away portion bearing against the roller 2. Disposed within the tube 7 is a shaft 10 carrying an endless screw 1,1. the tube 7 is fixed to discs 12 one at each end of the tube by means of which discs the tube ds fixed in position. In order ItO move the tube bodily to adjust the position of its scraper edge 9 relatively to the surface of the

* GB785758 (A)

Description: GB785758 (A) ? 1957-11-06

A new or improved process for improving the electrical resistivity ofconcrete sleepers

Description of GB785758 (A) Translate this text into Tooltip

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The EPO does not accept any responsibility for the accuracy of data and information originating from other authorities than the EPO; in particular, the EPO does not guarantee that they are complete, up-to-date or fit for specific purposes.

PATENT SPECIFICATION 785758 Date of filing Complete Specification July 1, 1955. Application Date July 8, 1954. No 20077/54. Complete Specification Published Nov 6, 1957.

Index at Acceptance:-Class 140, P 3 (D: E: F 2: G 2: G 4). International Classification: -H Olb. COMPLETE SPECIFICATION A new or improved process for improving the Electrical Resistivity of Concrete Sleepers We, Dow-M Ac (PRODUCTS) LIMITED, a British Company, WILLIAM KENNETH ROBERTS, a British Subject, and FREDERICK JOHN BROWNE, a British Subject, all of Tallington, Stamford, Lincolnshire, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:The invention relates to a process for improving the electrical resistivity of reinforced concrete railway sleepers especially prestressed sleepers, it being found that the normal resistivity of such sleepers is too low for satisfactory operation of electrical track signalling devices. Many proposals to impregnate concrete articles with other materials have been made and in some cases the impregnating materials have been specifically intended to improve the electrical resistivity of the concrete articles. The processes employed have in some instances included-the step of first drying the articles before impregnation The present invention is concerned solely with reinforced concrete railway sleepers, especially prestressed sleepers, in which the reinforcement provides conductive paths through the sleepers and with the problem of improving in a practical manner using practical materials the electrical resistivity between one rail and its attachment fittings and the other rail and fittings. The invention provides a process for the above purpose in which the precast reinforced concrete sleeper is first dried and is then impregnated throughout, or to a substantial depth, with grease, wax or other water-repellant material, such as that known as "Iranolin" (Registered Trade Mark), the drying step being sufficient substantially to remove moisture from the sleeper at least to the depth to be impregnated. According to a feature of the invention the grease or other impregnating material (e g a resin is used in solution or liquid form For example the grease may be in solution in paraffin, or paraffin wax in solution in paraffin may be used The material used is preferably solid or highly viscous at normal temperatures. In carrying out the invention the sleeper is first dried, at least to the depth of impregnation desired, by heating at about 50 to 1000 C or even up to 2000 C for say 6-12 hours. The drying may be accelerated by applying vacuum to the product, or it may be effected by vacuum alone The heating may be effected after the product has been cured or when it has been partially cured in which

case the heating may further or complete the curing. Usually, in the case of prestressed products, the initial load on the wires is released before the heating step but this is not essential The heating may be effected wholly or partly by passing electric currents through the product (e.g through the reinforcement or heating wires specially provided in the product). Alternatively the heating may be effected by steam or flame applied directly or indirectly. After the drying operation and while the product is still hot it is placed in a chamber and subjected to vacuum or, if vacuum is used for drying, that vacuum may be maintained. The liquid with which the product is to be impregnated is then admitted to the chamber, the liquid being for example wax or grease thinned with paraffin, or a resin in solution A pressure is then applied to the liquid to force it into the pores of the concrete The pressure employed may vary within wide limits (say to 3000 lbs /sq in) according to the depth of penetration desired, the type of product and the impregnating material being used In some cases a pressure of 50 to 200 lbs /sq in. is suitable but where the deeper impregnation is required a pressure of 2000 to 3000 lbs / sq.in may be necessary The pressure may be maintained for say fifteen minutes to one hour The pressure may be applied, for example, by a gas under pressure The gas may be inert such as nitrogen The residual gas pressure in the chamber may be employed to return excess impregnant from the impregnation chamber to a reservoir The impregnation may extend to a depth of about 2 to 4 inch. The impregnation may, if desired, be effected when the product is cold in which case it is important that if the impregnation material is normally solid or viscose, it should be thinned as described When the impregnation is effected hot however, the grease or other impregnant may be melted and a solvent be unnecessary. The impregnation may be effected in two or more stages 'or example after impregnation of the hot product as above described, with or without the use of pressure, it may be removed from the liquid, cooled, re-heated and again impregnated. To assist in obtaining effective impregnation, steps may be taken to increase the porosity of the surface of the product. The impregnating substance employed may be of a nature such as to assist in breaking up any film of surface water which may form on the concrete product in use. The invention may be applied to concrete as normally employed for the production of sleepers and consisting of Portland cement, sand and larger aggregates An important advantage of the invention is that the

strength of such products is maintained. Other impregnating materials which may be used are the silicones and synthetic resins such as those known under the Registered Trade Mark " Bakelite " The resins may be thermosetting and after impregnation the concrete product may be heated (e g to about 1500 C) to " set " the resin Bituminous materials, tar and glues may also be used. It will be appeciated that overall impregnation with a waterproof non-conducting material to a depth of say inch will, in most cases, serve as an effective insulation and will prevent moisture being absorbed and rendering the product conductive. It is not essential that pressure be employed to effect the impregnation Reliance may be placed on the capillarity of the concrete but it is preferred to employ pressure.

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