The Atlas Kwik-Stop is a large, heavy rope grab. It can be used as an ascender, but who would want to? The operating principle is interesting because of the unique way that it spreads the load out on the rope. I think that this idea could be used to make a better ascender for rescue situations where rescue crews like to shock-load the rope by dropping the stretcher team (why they do this escapes me, but it seems to be a major factor in their thinking).
The Kwik-stop has a U-shaped frame made out of aluminum. Inside is a sliding block with a U-shaped groove to fit the rope as well. The sliding block rides on the diagonal aluminum block seen at the middle of the device. This diagonal block goes through to the other side, and is removed top open the rope grab for inserting the rope. As the sliding block descends relative to the frame, the rope is squeezed over much of its circumference and over the entire height of the device.
Naturally, the sliding block must press against the rope with enough force to generate enough braking friction. This is ensured by the lever which pivots on an axle running through the sliding block (the center of the sliding block is hollow so there is room for the lever to move). When the lever is pulled down at the attachment point (the hook), the opposite end presses against the bottom of the diagonal block, which forces the axle and sliding block downward with respect to the diagonal block and the U-frame. A small spring helps to pull the lever upward to release the device.
I think that a much lighter and smaller ascender could be built to work on the same principle. The attachment hook and cold shut would not be desirable on an ascender because of their size and weight.
The Kwik-Stop is protected by U.S. Patent 3,811,155.
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©2007, Gary D. Storrick