Sizing

Manually Operated PWB Sheaves & Sheave Blocks

Sheave Block Use and Maintenance

Load ratings on all SuperLift sheave blocks are applicable to new or as new products only and apply to the maximum load which may be supported by the head fitting, under usual environmental conditions, shock loadings must be taken into account when selecting sheave blocks, as these loads are much greater than static loads. The W.L.L. or safety factor on all SuperLift products may be affected by wear, misuse, overloading, deformation, corrosion or other conditions, regular inspection must be carried out to determine whether use can be continued or the product withdrawn from service.
Experienced trained personnel familiar with tackle systems should rig SuperLift sheave blocks.
WORKING LOAD LIMIT - The maximum load or force the product is authorized to support in a particular service.
PROOF LOAD - The average force to which a product may be subjected to before deformation occurs.
SHOCK LOAD - A force that results from the rapid acceleration of a static load eg, jerking, these loads adds significantly to the static load.
STATIC LOAD - A constantly applied force or load.

Reeving of Sheave Blocks

When reeving a pair of sheave blocks one of which has more than two sheaves, the lead line should come off one of the centre sheaves of the upper block to prevent toppling of the upper block and possible damage to the rope. Always start reeving from the becket and avoid chafing the rope on the side plates. When you have completed reeving, the bottom block must be at right angles to the top block as in Figure 1. The upper block has a greater hook load due to the pull on the lead rope. The sheaves in these blocks revolve at different speeds, those nearest the lead line rotate at the highest speed and therefore wear out faster. For applications which require heavy lifting or high speed operation, bronze bushes or roller bearings should be specified when ordering.