Home : Technical : Trouble Shooting : Fixed Grip Lifts : Grips & Slippage

Thoughts on grips and slippage:

• The spring or spring pack is an indicator of force. It also applies a consistent force as the grip load changes.
• Worn, incorrectly sized or poorly designed springs will give false readings of grip force.
• Grip force testers will give a "more" accurate indication of grip force.
• Due to access most grip tests are performed with the carrier in stationary, non-loaded, and level position.
• Measurement of change between the movable components of a grip is a more accurate test of force, but is hard to measure considering the small distance of change.
• Manufactures will test the grip in different conditions, but it would be impossible to test a grip in all the possible combinations of conditions that many lifts would have.
• Ski areas should test their grips in its extreme loaded condition.
• Some designs of grips use the weight of the carrier to add to its gripping force.
• In some designs, carrier weight does not matter on its grip force.
• Grip slippage of 1' per 1000 hours is normal and helpful for distributing loads on wires.
• No slippage will cause broken wires.
• Riblet had conquered grip slippage; of course there's that pesky problem of broken fingers that you can not see until you pull the grip out of the haul rope.

Other real world conditions:

• Design did not work as built.
• Design works in most conditions.
• Manufactures are reluctant to pay for tooling costs for a new design, especially if this solves a small percentage of design problems.
• Manufactures are stuck with a bad design due to patent/design rights of other manufactures.
• Manufactures will boast about how they have solved the grip problem, but in reality it's the lift mechanic who fine tunes the grip force to slow down slippage.
• Lifts with extreme trap and or hold down assemblies can induce a grip to slip.
• Haul ropes with large amounts of twist can induce excessive grip slip.

I suspect you guys have been doing most of this stuff anyway, if you have any other comments feel free to post.