01 March 2008
Located in the scenic village of Reichenbach, Switzerland, Fritschi is the world's premier manufacturer of touring ski bindings. Its next-generation Diamir free-ride Alpine touring bindings, featuring a DIN setting of 12 and built-in brakes, allow skiers to go off the beaten path, enabling them to walk uphill in their skis.
The bindings are hinged at the toe, so when they are released at the heel, conventional downhill skis can be used as touring skis. To facilitate this movement, each binding incorporates two 5mm inside-diameter, 10mm long, self-lubricating bearings, which are press-fitted into the hinge assembly at the front end of the polyamide-moulded part. For normal descent, the heel of the binding is clamped to the ski, preventing it from moving.
Manufactured by plain bearings specialist, GGB, the bearings are exposed to harsh environmental conditions - both moisture ingress and temperatures that can range from -30ºC to +30ºC. Moreover, the loading on the bindings when curves are negotiated, can reach two to three times the body weight of the skier. The high forces and shocks of downhill runs subject both the skis and bindings to bending moments that can induce some movement in the hinges. During walking, there might be a 60-degree movement every half-second under relatively light loading, because the skier's weight is shifted from one foot to the other. Typically, the service life of the bindings is several hundred hours.
The principal properties Fritschi sought in these bearings were low friction and maintenance-free performance. With a coefficient of friction 0.02-0.25, GGB DU, bearings offer good friction performance in rotating, sliding and oscillating motion applications. They can withstand static loads of up to 250MPa, dynamic loads of up to 140MPa, speeds up to 2.5m/s and temperatures ranging from -200ºC to +280ºC.
The bearings consist of a rigid steel backing, which provides high load-carrying capacity, while a porous bronze inner layer impregnated with a homogeneous mixture of PTFE and lead provides the required lubricity and longevity.
Fritschi produces hundreds of bindings a day and uses up to 300,000 bearings a year. To date, the company has reported no problems with either its products or the bearings.
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