ISC Large Rigging Pulley for Rope up to 25 mm

The ISC large rigging pulley takes rope up to 25 mm and is built for heavy arborist rigging, where big wood and large-diameter lines demand a bigger sheave. The grey frame with red wheel makes it easy to tell apart from smaller pulleys on the truck.

Where it fits in a rigging system

A rigging pulley replaces a natural crotch as the redirect for your lowering line. Hang it from a rated sling on a sound anchor above the work, run the rope through the sheave, and take it down to a lowering device at the base. The ground worker gets steady, predictable friction from the device instead of uneven crotch friction.

Size it to the rope and the load. The pulley and anchor see roughly twice the rope tension because the line pulls from both sides, and pieces that fall before the catch add shock load. Keep drops short and let the rope run slightly to soften the stop. Check ISC's published ratings before sizing it to a job.

A large pulley is heavy, so most climbers set the anchor sling first and haul the pulley up on a line rather than climbing with it.

Inspection and care

Spin the sheave by hand and make sure it runs smoothly with no wobble. Look for cracks, bent side plates, wear grooves, and loose fasteners. Retire a pulley that has been dropped from height onto a hard surface or overloaded. Compare models in our rigging blocks section.

Rigging forces are dynamic and can be several times the weight of the piece. Follow the manufacturer's ratings and ANSI Z133, inspect every component before the job, and keep rigging work to trained crews.