Differential with hypoid gears
In practical class we dismantled a differential and inspected the condition of each component in the diff housing.
We first marked the diff housing caps and marked the crown wheel position this is so that when the diff is reassembled when we can correctly align the housing and crown wheel.
We then removed the diff case assembly, unlock & removed all the crown wheel bolts and removed the crown wheel with all components in the diff housing.
Driven gear assembly inspection
Condition of crown wheel teeth
The condition of the crown wheel teeth is good; there were no pits around the teeth. This can be caused small bumps on the teeth of then pinion gear when the teeth contact.
The teeth of the crown wheel were smooth and no indentations were found that can be caused by a large load on the contact between final drive gears.
The crown wheel is driven by the pinion gear which drives the side gears.
The crown wheel supplies the power to side gears in the diff housing and finally transmitted out to the wheels
Condition of the crown wheel bolts
The crown wheel bolts had some rounding on the top caused by wrong socket or spanner size, overall the threads were in good and not cross threading were found.
The crown wheel bolts hold the crown wheel on to the diff housing with a total of 10 bolts
Removing and condition of the cross shaft
Removing the roll pin we first had to tap out the cross shaft, the taping the pin with a brass punch. The roll pin had some small scratch marks around the shaft maybe caused by removing of the shaft but are not serious.
Spider gears
The cross shaft sits in between the side gears to hold the gear assembly in place with a pinion shaft to lock it in place, there are flat surfaces on the shaft which allow for lubrication.
Spider gears
Removing the spider very easy by rolling the side gears around until the spider gear fall out by their own. We found no thrust washers on any of the gears in the diff case.
Some of the spider gears had small marks on the face of each teeth, this is because of the pinion gear is to far forward to correct the alignment we would have to place some shims on bring the pinion gear back for proper teeth contact.
The spider gears walk around the side gears when the vehicle is turning, the spider gears allow for the inner wheel to rotate slower than the outer wheel when turning. When the vehicle is driving on a straight road the spider gears do not walk around the side gears and only turn with side gears
Side gears
The side gears hade some rust on the teeth which can cause pitting and will eventually have to be replaced. The side gears also have small indentation on each tooth which looks like line after line groves it could be manufactured like this for a purpose.
Pinion gear
The pinion gear was very smooth when we removed it from the case some of the tooth had small chips on the tips which was most likely caused by incorrect tooth contact
The purpose of the pinion gear is to drive the crown wheel; the pinion gear is connected to the drive shaft, also the pinion gear is positioned at the center of the crown wheel with hypoid gear tooth
Diff case
The purpose of the differential housing is to house the side and the spider gears
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