Too much traction

Interested in hearing what has been done in the past when the counterweights or the car gets hung up and the car or the counterweights keep traction? We were doing an annual test today, and when the car safeties set the counterweights kept going. Very intimidating when you have cables spooled on top of the car and the only thing holding the counterweights up is the traction of the cable in the sheave.

It has been locked out until we get to the bottom of this.

Is the safeties and governor contacts cutting the safety circuit properly and dropping the driving motion to the traction machine, so its not driving a little after the gear is in?

Is the drive sheave worn out?

Full wrap or half wrap?

This was during a test. We had the electrical circuit jumped. It should have lost traction.

The sheave could very well be worn out.

Half wrap.

Ah of course my bad!! I wonder if the sheave isn't the right size for the ropes, ie too tight?

I'd think that if the rope crowns are even with top of the driver, it might be too worn. Uh, how'd you get the slack taken back up on the car side, bump the drive up?

Yes, short of bringing in the hoist and rigging, that was the quick solution. We caught it in time when only 6 or 8 inches of slack was in the ropes. Still too scary and have not seen this before. Unless, somebody has a better solution we are replacing ropes and drive sheave.

Way too close to Halloween for this to happen.

Had this happen during construction once. 2:1 gearless double wrap TK equipt. We didn't have rope retainers on yet. The car was on the buffer, ran the wrong direction, it picked the counterweight, the ropes on the car sheave slacked about 2' and crossed up in every possible way. Then traction broke and pulled the ropes tight in a rats nest on the car sheave. Maybe 35 floors of rope was enough weight to keep traction for a sec. Never ran a car without rope retainers again!

From my old notes the rope would sit around 55% of diameter below the cross line of the vee groove across the whole 4 to 6 grooves. Any more than that, and there is wear and may stick and cause too much traction.

What kind of Machine is it? I know it's not a KONE, because they slip when their not supposed too. Even the 2 to 1's slip.

This is a Dover machine 86 model GD-105

You could call a sheave regrooving specialist. We use tucker grooving. Great company to work with. Very knowledgeable.

One easy thing to look at would be lang lay ropes rather than regular lay ropes. Lang lay ropes will provide more traction, usually used in U-groove sheaves. If using lang lay ropes in v-grooved sheave, may be too much traction.

Matter of interest when do you jump the plank switch etc during the test ? The way we do it down here ( in the Caribbean ) the inspector likes to trip the governor ( then short any governor jaw switches or os switches ) then drive it until the plank switch breaks , only at that point do we jump the plank switch , and drive it a little further until it breaks traction or the drive quits .
I've not had one not break traction yet ...thank god , can imagine that's a ' oh s**T moment right there.!