There are a lot of railcars wheels are being replaced due to “High KIPs”. We toss these terms around without really understanding what they mean.
So what is a KIP? There are a couple of definitions of a “kip”.
One definition is “a gymnastic exercise performed starting from a position with the legs over the upper body and moving to an erect position by arching the back and swing the legs out and down while forcing the chest upright”. I can’t even figure that out much less try it without major injury to this old body.
90 KIP force is greater than 2 1/2 times the fully loaded 286K GRL wheel at rest
For use in the rail industry, the term KIP is engineering slang for 1,000 pounds-force. So, a 90 KIP wheel is a wheel that is generating 90,000 lbs. of force when measured by a wheel impact detector.
For comparison, the wheel static load for a fully loaded 296,000 Lb. GRL railcar is 35,750 lbs at each wheel. So the 90 KIP force registered for a single wheel is greater than 2 1/2 times the static load. This force goes two ways. One way is into the track and track structure, not a good thing for the track. This force is also going into the railcar – the old “equal and opposite” equation; also not a good thing for a railcar.
So yes – High KIP wheels are a major cost driver for car owners. But so are high forces going into the track and going into the railcar.