CREATIVE JOURNEYPAUL RYAN, JONATHAN CHOW AND YALAINDRA SHUGUMAR

REQUIREMENTS- Had to lift 8Kg weight- Had to lift it a height of 0.5m- Made only from acrylic sheets & Glue- Should not fail (crack/fail)- Gearbox needs to be optimised

HOW IT WILL BE EVALUATED- The grade for its performance is derived from the

performance equation

- Which then will be used to allocate a score- 10% + 10%

OUR APPROACH-We first looked at the performance equation-found which were constants-determined the motors influence on the equation-this led to whether we want it to be reliant on efficiency or power-This brought the variables t & D to discussion-We will apply a factor of safety-Over engineer by 20%

WHAT TYPE OF GEAR IS MOST SUITABLE- Through calculations of the performance we looked at the difference between variables- We then compared these to discover the

types of gears we wanted to use- Originally we wanted helical

ADVANTAGES AND DISADVANTAGES OF EACH

Spur Gear+Good at low speeds -Low amounts of +Torque+Easy to cut -Very noisy

Helical Gear+High capacity for Torque -hard to manufacture+Less noise

Worm Gear+Holds position when stopped -Inefficient+High capacity for Torque -Bad at high speeds

GEARS

•Gears are used to increase speed, or to increase torque•Conservation of Energy law states that the total energy in a

closed system remains constant; energy cannot be created or destroyed. • Therefore any increase in speed would have to be

accompanied by a decrease in torque, and any increase in torque, would result in a decrease in speed.

GEARS

• In order to increase speed• Energy applied to a large gear, which is connected

to a smaller gear• In order to increase torque• Energy applied to a small gear, which is

connected to a larger gear

GEAR RATIO

• A Gear Ratio is the ratio of the number of teeth between two gears.

E.g. a 48 tooth spur gear to a 16 tooth pinion would have a gear ratio of 48:16, which factors down to 3:1. • For every revolution of the 48T spur gear, the 16T pinion gear

rotates three times. • Using the gear ratio of a set of gears, we can calculate the output

speed/torque from the input speed/torque.

GEAR RATIO

•Using a 3:1 gear ratio• Energy in: Motor at 900rpm, 60Nm. • Increase in speed (Energy applied to the large gear, 3:1 ratio) • Energy out: 2700rpm, 20Nm

• Increase in torque (Energy applied to the small gear, 1:3 ratio) • Energy out: 300rpm, 180Nm

GEARBOXES

•Gearboxes usually contain multiple sets of gears• This allows for a greater gear ratio in a smaller

space• The gearbox ratio (total gear ratio) of the gearbox

would be determined by multiplying the individual gear ratios of each set of gears• E.g. A gearbox containing three sets of gears, with

the ratio 3:1, 4:1, and 5:1 would have a resultant gearbox ratio of 60:1 (3*4*5=60)

ENERGY TRANSFER

• There will be losses in a physical gearbox system due to multiple factors• These factors include: • Friction•Backlash (Slip) • Imperfect meshing of gear teeth

GEARBOX EFFICIENCY

OPTIMIZING THE GEARBOX

• In order to optimize the gearbox, we would need to calculate the torque required to lift the weight•Once that’s done, we would need to increase our

goal torque by 20% as a factor of safety. This is so that we don’t overwork the motor. • Then, we would calculate the required gearbox ratio,

and thus the number of teeth in each set of gears

GEAR ARRANGEMENT:

- Our gear arrangement will be a Compound configuration with a step reduction in each set.

- The number of gears that will be in the configuration is still being assessed.

- The gear configuration needs to be strong to withstand the forces of the weight.

Housing for the gears (Gearbox):

The housing for the gearbox will have some space on either side of the step compound gears which may leave room for movement of the gears, to prevent this we are considering creating bushings to prevent any significant movement of the gears. The shape of the gearbox may look something similar to the shape of a bike chain configuration or we may decide on choosing just a regular rectangle shaped box to avoid stress fractures near the edges or near the output shaft.