Zip Line Trolley and Pulley

The double wheel trolley is often used for zip lines. Double wheel in-line trolley rollers prevent the side-to-side twisting. Trolleys need to be built with a strong bearing capable of withstanding the forces encountered during the ride. The following trolleys are popular double wheel types.

Petzl Tandem Speed Pulley is used for cable sizes 1/4 to 3/8 inch, or 12 mm maximum, and speeds of 10 meters per second. This trolley has a dual pulley system which helps it track straight and reduce twisting. The trolley is opened and clipped around the cable then secured with the locking carabiner, which also connects the lanyard to the harness, to prevent it from coming off of the cable during the run. This zip line trolley has aluminum in-line sheaves mounted on self-lubricating bushings and side plates designed especially for movement and torsion encountered on a zip line. It can accept up to three carabiners for various purposes, including a backup lanyard run to a separate steel carabiner on the cable.

CMI Velocity Trolley is made for use on ropes courses and zip lines with maximum cable diameter of 1/2", 13 mm. It has high strength and provides a separate attach point for an additional locking carabiner. The additional attachment provides access for a backup or line to return the zip line trolley back to the starting position when done. As a backup, a separate steel carabiner is connected by lanyard and runs to another steel carabiner which the cable runs through. The CMI trolley is versatile and can be used with complex cable systems such as found in canopy research. The casing is made with strong stainless steel. It uses bronze bushings made with a sintering process that creates microscopic porosity in the bronze allowing lubrication to retain inside the bearing. This zip line trolley is 5" or 125 mm and has a width of 3" or 75 mm. It weights 3/4 pound or 1/3 kilogram. The CMI Velocity zip line trolley has a work load limit of 1,400 pounds, or 623 kg.

CMI Cable Trolley SS has an extremely high breaking strength at 14,000 pounds and excellent performance as a zip line trolley. It has stainless steel sheaves and has sealed ball bearings. The axle is stainless steel. It is made for rope or cable of 1/2" or 12.5 mm in diameter, weighs two pounds or 900 grams and has an attractive stainless steel finish. The CMI Cable Trolley SS is 6-1/4" x 6" in size. It also has a separate attachment point for an additional 'biner for backup or return pull line. The stainless steel makes it able to withstand the elements and provides corrosion resistance.

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Add Comment...what worked, what didn't, lessons learned and tricks and tips.

Comment Sent in by: Mike
A great way to tension your cable. I drilled a hole in a piece of 4x4 about 10 inch long(of which is also my brake) it as two eye bolts attached. I put the 4x4 on the cable and attached a cable clamp as a stop. I purchased a 12v winch from Northern Tool with 30 feet of cable. (just $49.00 on sale Item# 141220) I strapped the winch to the tree ( it came with a bracket) and the cable hook to the eye bolts. I used a short strap to both sides of the 4x4 for an even pull. It was four times faster and much faster than my first try with a come-along and chain. [Reply]