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: Block and tackle by quinet, CC BY 2.0
A compact ISC rigging pulley for 5/8 in rope.
The ISC small rigging pulley for 5/8 inch rope packs a rigging redirect into a compact red frame with an orange wheel. It is a good fit for limb lowering and lighter removal work where a full-size block is more than you need.
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 | 5/8 in |
|---|---|
| Size | Small |
| Color | Red frame, orange wheel |
| Use | Arborist rigging pulley |
Specs are from the manufacturer's published figures where available. Confirm against the product listing before you buy.
A small pulley is lighter and easier to carry for limb work. Choose a larger block when wood gets heavier or loads become more dynamic.
Colors help crews pick the right size quickly from the gear bag. Always confirm the rope size and rating on the pulley itself.