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Squeeze Brakes

Most descenders generate the friction by bending the rope around the surface of the descender. The change in direction generates a normal force that generates friction that is nicely approximated by the well-known snubbing formula. But what if we want to eliminate the bend? There has been a lot of interest in that idea, leading to the development of squeeze brake descenders. A control systems theorist might immediately recognize that this would lead to instability, and that is exactly what the experimenters found out.

Squeeze brakes have a straight rope path. They obtain their friction by compressing the rope between two plates, and not by snubbing. Standing in the drop zone under the rappeler with the idea of providing a bottom belay won’t work with a squeeze brake. Without snubbing, adding tension below the brake does not provide more friction and does not slow the rappeler – in fact, it tends to do the opposite. Similarly, using one’s braking hand does not better below a squeeze brake than it would above the brake.

I’m not going to go into details of their history, but refer the reader to Kirk MaGregor’s 1986 article “Squeeze Brakes Up to 1982” in Nylon Highway #22.. Kirk was one of several who tried a basic squeeze brake, and in his own words found, “Its speed fluctuated randomly over a wide range as it moved down the ropes, making accidents likely.” Others had similar experiences. Most people abandoned the squeeze brake idea after Sara Corrie’s severe, near-fatal accident in 1978. If you want to try squeeze brakes, please first modify your will to leave all your assets to me.


Image ID Device Description Acquired Weight Height Width Thickness Std. volume
Mar-Mex Escapeline 464 Mar-Mex Escapeline Squeeze brake with horn, extruded sides, soft anodized, plastic knob John E. Weinel, Inc., 1985 383 75 104 93 725
Storrick   - MacGregor Squeeze Brake 3056 Storrick - MacGregor Squeeze Brake
2 Al-side plates /w control crank & spring, nutcracker handles, cable connections Gary Storrick, 2021 1454 305 155 59 2780
Storrick   - Adams Fire Escape Device 3254 Storrick - Adams Fire Escape Device
2 Al side plates, U-shaped rod hinge/eye,  control screw on swinging gate Gary Storrick, 2023 670 147 83 75 920
Storrick   - Rabelos Fire Escape Device 3260 Storrick - Rabelos Fire Escape Device
2 hinged Al side plates,  control screw on swinging gate, hook on rear plate, D-ring eye Gary Storrick, 2023 757 185 82 102 1546
Storrick – Zachariasen Musicbox 3252 Storrick – Zachariasen Musicbox
Squeeze Brake, 2 Al side plates /w pressure platelever, control screw on swinging gate Gary Storrick, 2023 622 222 80 60 1069
Storrick – Zachariasen Son of Musicbox 3251 Storrick – Zachariasen Son of Musicbox
Squeeze Brake, 2 Al side plates /w sliding pressure plate, pressure spring, control screw, bar /w eye, 2 QR pins Gary Storrick, 2023 1113 159 124 70 1375

Squeeze Brake Weight Chart