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Almen found that wheel bearings were damaged before they were used by customers. Furthermore, he found that the bearings were more damaged for long-distance shipping of the cars and that the season of shipping also had an influence. The reason for the damaged bearings were micro-oscillations [17] which occurred due to the shipping. The small ...
Wheel bearing rolling resistance is lowest with high axle loads and intermediate speeds of 60–80 km/h with a Crr of 0.00013 (axle load of 21 tonnes). For empty freight cars with axle loads of 5.5 tonnes, Crr goes up to 0.00020 at 60 km/h but at a low speed of 20 km/h it increases to 0.00024 and at a high speed (for freight trains) of 120 km/h ...
A ball bearing. A bearing is a machine element that constrains relative motion to only the desired motion and reduces friction between moving parts.The design of the bearing may, for example, provide for free linear movement of the moving part or for free rotation around a fixed axis; or, it may prevent a motion by controlling the vectors of normal forces that bear on the moving parts.
Thus, the contact between ball and race is of finite size and has finite pressure. The deformed ball and race do not roll entirely smoothly because different parts of the ball are moving at different speeds as it rolls. Thus, there are opposing forces and sliding motions at each ball/race contact. Overall, these cause bearing drag.
In many applications tapered roller bearings are used in back-to-back pairs so that axial forces can be supported equally in either direction. Pairs of tapered roller bearings are used in car and vehicle wheel bearings where they must cope simultaneously with large vertical (radial) and horizontal (axial) forces.
Locking hubs, also known as free wheeling hubs are fitted to some (mainly older) four-wheel drive vehicles, allowing the front wheels to rotate freely when disconnected (unlocked) from the front axle. This is done to reduce the mechanical resistance of the front-portion of the drivetrain when four-wheel drive is not in use. [1]
When the engine is cool or even at normal operating temperature, the fan clutch partially disengages the engine's mechanically driven radiator cooling fan, generally located at the front of the water pump and driven by a belt and pulley connected to the engine's crankshaft. This saves power, since the engine does not have to fully drive the fan.
The usage of the bearing has three major advantages: (i) pumped water going through the bearing is conveniently used as a lubricant, which reduces pump operation cost; (ii) water flow takes away heat and fine particles through the bearing grooves; and (iii) the natural resilience of rubber gives the bearing good properties for shock and ...