PROJECT REPORT OF ELECTRIC LOCO SHED, KANPUR

SMI – 64/M-3 SECTION

STATIC BALANCING OF AM – 12 TYPE PANTO

What is pantograph??

• A pantograph for rail lines is a hinged electric-rod device that collects electric current from overhead lines for electric locomotives.

• The pantograph typically connects to a one-wire line, with the track acting as the ground wire.

HISTORYThe first flat slide-pantograph was invented in 1895 at the Baltimore & Ohio Railroad and in Germany in 1900 by Siemens & Halske. The first day of service of dimond shape pantograph is 26 october 1903.

Main parts of pantograph

(1.) Lower arm assembly – (a.) Lower pantograph arms(b.) Lower arm spindle (2.) Working springs

(3.) Push rod(4.) Upper longitudinal rods(5.) Over head equipment or OHE

(6.) Centre articulated system

(7.) Shunts

(8.) balancing rod

(9.) Air motor/ servomotor – (a.) Air motor cylinder(b.)Piston/rubber bucket(c.) Holding down springs(d.) Air supply line/pipe(10.) Insulated control rod

TECHNICAL DETAILS

• Weight of all types of pantograph of this series will be within 235 kg approximate including all accessories but without foot insulater.

• At the collector head metallised carbon strip of 3.5 mm is used.

• In air motor 3 holding down springs are used.• Bi- metal plate/washer(aluminium+copper) is used as a shunt.• Upward travel time of panto from 0 m to 1.5 m should be 6 to

10 sec. & downward travel time 1.5 m to 0 m should not exceed 10 sec.

• Insulators have approximate height of 360 mm on roof.

PRINCIPLE• When the pantograph is at lowered position,

the working springs are extended by holding down springs in air motor cylinder which acts through the insulated control rod.

• Basically, compressed air raises and the holding down springs lower the pantograph.

• When the pantograph is working and the normal working air pressure 7 kg/cm2 is maintained in the air motor, the position is kept still with the articulated system kept raised only by upspring device and is entirely free.

WORKING OF PANTOGRAPH

• RAISING - when the compressed air is admitted into the air motor cylinder, the piston compresses the holding down springs inside the air motor and displaces the control rod thus permitting the rotation of lower arm spindle under the action of working springs. The pantograph rises until the collector head reaches the overhead wire.

LOWERING – releasing the compressed air in the cylinder causes the piston to return under the action of the holding springs,

control rod engages and lowers the pantograph

What is static balancing??

• OHE applies its weight of 7 kg in downward direction so to kept the pantograph in its raised position it needs to apply a load of 7 kg in upward direction to balance the panto.

• For this we use compressed air in the air motor cylinder which has working pressure 7 kg/cm2.

• This counter balancing is called static balancing of pantograph.

STATIC BALANCING PROCEDURE

• To obtain the balancing of the pantograph on the roof of loco, compressed air pressure in air motor cylinder should be set at 7 kg/cm2.

• For balancing a panto on the shop floor fixture, air motor may not be coupled.

• In the factory the panto is balanced with 7 kg load.

• Before starting balancing ensure the application of graphite grease.

• Srew the all four regulating/adjusting screws as much as possible towards the spindle centre.

• After placing 7 kg load on the collector bow, balance the articulated system to a height of 1.75 metre marked in the height gauge by stretching or retarding main springs.

• Repeat the same procedure to balance the articulated system at heights 1.5 m, 1 m & 0.5 m.

• NOTE – do not try to increase the tension of main spring after completing the counter balancing.

CAUTION

• To avoid accidents – • Never to climb on the roof when the

pantograph is in contact with the catenary or to make absolutely sure that it is not LIVE.

• To check that the pantograph is suitably retained on its low stop before climbing on the roof.

THANK YOU!!