190303i final drive fundamentals and service Flashcards
What is the main purpose of a final drive?
It provides the last remaining gear reduction in the overall vehicle powertrain
Why are off road and heavy equipment final drives built so heavy and durable?
Due to the high forces and stresses often generated by overloading, overworking and abuse the machine is required to do
What are some common gearing configurations?
pinion and bull gear sets, planetary gear sets, chain drives or a combination of these
What are the two planetary mounting arrangements? and where are they mounted?
Outboard mounted: planetaries in a housing visible without the tire removed and Inboard mounted: planetaries mounted on an internal housing before the drive axle and tire assemblies
If an inboard set up is used, what component is required to be used with it?
a larger output shaft leading to the wheel hub or sprocket to handle the torque load.
What advantages does an outboard final drive set up provide?
torque is increased right at the wheel and ease of maintenance and servicing the final drive
Why do chain drive sprocket final drives between two sides require the same tooth count?
so both tires rotate in the same direction at the same rpm
A chain in a final drive is lubricated by?
a housing filled with enough lubrication oil to submerge the lower part of the sprockets, which would allow for splash lubrication to the chain and bearings
Is metal generation normal in a chain drive final drive housing? even when lubricated?
Yes this is normal, check manufacturer’s specifications for wear limits on the chains and sprockets before determining it is ok.
What design feature is unique to motor graders pertaining to suspension travel?
The final drives utilize a walking beam system, allowing the chain case to pivot in the middle of the case for a sort of “suspension” to the final drive
What condition should the planetary on a final drive operate as?
a gear reduction
What is the common planetary arrangement (input and output) for a final drive and explain what is driving/holding them
Sun gear is the input (splined to the end of the drive axle), the held member is the internal gear, and is splined to the spindle end of the axle housing, the carrier is the output, which is fastened to the wheel hub assembly
in a haul truck, what is the output for the entire final drive system, if the input were to be the sun gear, followed by the internal gear being held, then the carrier supplying power to the 2nd planetary input, which is the sun gear? and what is the condition the gear set is in? (not multiple choice)
A. the second carrier
B. the first internal gear
C. the second sun gear
D. the first planetary pinions
A. the second carrier would be the output, and it would be a double reduction first speed
What are the 3 advantages of a chain final drive?
Have a single input, but multiple outputs, efficiently transmit torque without slippage, across greater distances and provide a gear reduction to facilitate torque multiplication
Where are the brakes commonly located on a motor grader and what type are they? and how are the applied?
the wheel hubs on the ends of the chain case, they are usually wet discs, they are air applied and spring released
Why is an AC electric drive better than a DC electric drive?
higher efficiency than a DC system, dc system uses mechanical switches, which are slower to responding and prone to arcing. AC motors use no moving parts
List some benefits of AC electric drive equipment:
30000 benchmark hours of use is common, maintenance free, motor is swapped as a complete unit, making down time less, diesel engine runs at a constant speed and lack of shift shock increases drivetrain life.
Mechanical drive haul trucks are more fuel efficient than electric drive True or False?
False
An electric motor can utilize its own electric generation to slow itself without any other component? true or false?
False, it requires an inverter, and a dynamic retarding grid and fan
Explain the flow of AC to DC conversion in an electric drive hauling truck:
starts at the main generator at the back of the engine and gets changed to DC current either before the DC bus, or at the DC bus, from the DC bus it heads to an inverter where it converts back to AC power so the AC motors can utilize the power.
What is the output/input system comparable to in regards to power/current generation in an electric drive vehicle?
it is comparable to an alternator
What is considered the “BRAIN” of an electric haul truck?
the main control group
what helps smooth out and filter DC voltage spikes?
a capacitor
