Various Kinds Of Sack Truck Wheels

By Author: Carn Gerrish
Total Articles: 26
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The castor is a combination of complex and elaborately secured parts that need to work together for optimum function. While the wheel, the axle, mounting plates, upper and lower raceways, wheel bearings, and roller bearings, are vital parts, the yoke in particular plays a vital role. The existence of the yoke is the deciding factor between a castor and a regular wheel. For a wheel to become a castor, it needs to be assembled with a castor yoke and axle.

The yoke of a castor plays an important function in securing the mechanism, and therefore warrants special attention. It is a gadget with 2 �legs� potruding outward, much like the blades of a pair of scissors, except in the case of the yoke they do not meet at a connecting point. These two 'legs� are case hardened vertical extensions of a piece of horizontal metal. The yoke can also be a piece of single formed steel with two case hardened �legs� welded to each side. The wheel is placed between these legs and is held in place by the axle which is passed through the outside of one part of the yoke, through the axle hole of the wheel, ...
... through the wheel bore, and finally through the axle hole of the opposite yoke. More often than not, the mechanism is secured with a hex head bolt and hex nut. The caster yoke further holds up both the top and lower raceways. These raceways are the roller bearings that �race� between two formed pieces of steel thereby helping the castor to swivel. In addition, castor yokes differ according to the allocated castor load categories. Those attached onto heavy duty and extra heavy-duty castors are technologically superior to those on light and medium duty castors.

The mounting plate that is the connection point between the castor and the piece of machinery or furniture is fixed onto the yoke. The two basic types of yokes determine a primary distinction between castors-the swivel and rigid castor.

Swivel castors come attached with a swivel yoke. They allow the fork legs and the attached wheel to rotate 360� providing absolute freedom of mobility. The other is the rigid caster that does not provide any freedom of mobility. Their swivel counterparts are not as sturdy as they are because rigid castors have a strict bi-directional movement that is paramount for stability. While swivel castors allow freedom of mobility along those dicey corners and areas, they have a knack to sometimes head in a direction other than the decided direction. In addition, for rigid yokes, the �legs� are not offset, instead they are straight providing added security.

During maintenance and routine checks of material handling equipment, it is vital to inspect the yoke, axle, the hex head bolt and hex nut holding the caster wheel in place. A lose axle would detach the yoke from the wheel, causing injury and accident, not just to the goods, but also to the handler and probably those standing around.

Thus, it is evident that the yoke of a caster plays an important role in its operation. Minus the yoke, the caster would merely be a wheel. Not only does it add to caster definition, it also guarantees that the wheel is securely in place, making it safe for designated weight loads or terrain.
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