How to Measure Wire Rope, Sheave and Grooves

Choosing the correct size of sheave when working with wire rope depends on knowing the correct diameter of the wire rope and a bit of arithmetic. Knowing the correct diameter of the wire rope depends on the unlikely combination of an adjustable wrench and a measuring tape. When all of these elements are combined, you will know how to measure wire rope and select the proper sheave to use with that rope.

Measuring Wire Rope

• 1

  Open the jaws of an adjustable wrench wide enough to allow the largest diameter of the wire rope to fit.

• 2

  Turn the wire rope and adjust the jaws of the wrench so that the widest part of the rope is barely in contact with the surface of the jaws. The diameter of wire rope is the largest diameter, measured across the outside edge of two opposing strands of the rope.

• 3

  Remove the wire rope from the wrench without moving the jaws. Measure the distance between the surface of the upper and the surface of the lower jaws of the wrench with a tape measure. The measurement between the jaws is the diameter of the rope.

Selecting the Proper Sheave

• 1

  Measure the diameter of the wire rope you want to reeve through a block. The diameter of wire rope is the largest diameter, measured across the outside edge of two opposing strands of the rope.

• 2

  Multiply the diameter of the wire rope by 20.

• 3

  Use a block with a diameter of at least 20 times the diameter of the wire rope. For example, if the wire rope is 1/2 inch in diameter, 20 x 1/2 = 10; use a sheave 10 inches in diameter. If the answer isn't a whole number---say the result of multiplying by 20 is 30 13/16---round up to the next whole number for the correct sheave size.

  (See reference 2)