When you are talking about wheels, you are talking about the rim or wheel (figure A). The black part is the tire. The tire and wheel touches the ground in only four places and it is a contact patch only about the size of your wrist.
Tire and wheel assemblies bolt to either disc brakes or drum brakes in the front or rear. Inside the drum brake there is an axle shaft (figure B) that goes round and round. Inside the shaft is a grease seal and behind that a bearing that causes the axle shaft to go round.
Figure A
Figure B
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The grease seals keeps the gear oil from behind the axle from coming out. The roller bearing carries the weight of the vehicle and allows the axle to rotate on the small roller bearings. This is on the rear axle system.
On front wheel drive vehicles, you have a seal bearing (figure C). You cannot see the ball bearings; just a rubber seal around the edge and inside are the rolls of roller bearings that carry the weight on the front wheel drive vehicle.
If you have rear wheel drive -- disc or drum -- you have tapered roller bearings (figure D) and they are located on the outside and inside of the hub and they carry the weight of the vehicle.. They ride on what is called a race (figure E) and they have to be repacked periodically with grease or they can wear out and ultimately cause the vehicle to have a malfunction.
Safe Young Drivers: A Guide for Parents and Teens
1889324035
Phil Berardelli
(November 1996)
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Nautilus Communications, Inc.
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