CMI
CMI 5/8" Steel Arborist Block
A steel-sheave rigging block for 5/8 in lowering lines on removal work.
Rigging Blocks
Representative photo. Check the retailer listing for the exact model, color and size.
Photo: Pulley Block Equipment Rigging Edited 2020 by chimpwithcan, CC BY 2.0
A compact ISC rigging pulley for 1/2 in rope and light lowering.
The ISC small rigging pulley for 1/2 inch rope is a compact redirect for light rigging, limb lowering, and pruning jobs where weight in the tree matters. The red frame and grey wheel make it easy to grab the right pulley for a half-inch line.
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.
The small frame rides on a saddle without getting in the way, so you can set it as you climb and keep moving.
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.
| Rope size | 1/2 in |
|---|---|
| Size | Small |
| Color | Red frame, grey wheel |
| Use | Light arborist rigging |
Specs are from the manufacturer's published figures where available. Confirm against the product listing before you buy.
For light limbs and small wood, often yes. Move up to a larger pulley and rope when pieces get heavier.
Colors help crews pick the right size quickly from the gear bag. Always confirm the rope size and rating on the pulley itself.