Got an old traction machine, i am trying to keep running till a new machine get here. its a 1,800# car running at 100 fpm.
The unit is binding and causing the drive to fault out. I did a die test and the pattern is attached, The strange part is in the down, I show no wipe at all , but down runs smooth, the bucking is in the up direction. When I lift the spider the bucking in the up lessons, but the down then starts to buck as well. The drive only trips an overload in the up still. The wipe pattern remains the same , nice contact in the up and no wipe in the down. This is done with the weight of the empty car on it. If I hang the car unit runs smooth.
Why do I have no wipe in the down? For shits and giggles, I tried lowering the spider, and as expected the unit bounds up solid even taking out 15/1000
Any suggestions to keep this gar running 6 more weeks?
If you drop the brake and rock the drum back and forth by hand you should feel a slight bit of movement from one side of the ring gear to the other. Like maybe 5 to 7 thousandth. have you checked the thrust bearing?
John Jay: We actually just had Titan machine convert the shaft to a new style trust bearing, the original was a two piece design was trashed. There is about 0.020 of backlash , so it's really worn, units 90 years old. The last mod didn't get a new machine. I found signs of the machine running with no lubricant at some point, lots of inclusions on the gears , and 4 deformed teeth that I had to clean up with a dremal, but nothing else really out of line for such an old machine. Ive never seen no wipe on one side of the teeth before .
I would bet that the new thrust bearing is the culprit. In a basement machine, the force on the sheave pulling up instead of down affects the worm and ring a little differently than in a normal overhead-type configuration. Did the unit run correctly after the new thrust was installed? Also, 20 thousandth is way too much.
I know the 0.020 is way to much, the machine was not well maintained over its life. I don't think anyone every changes gear lube anymore, seems like every new one I get on service and pull off the inspection covers to clean them out and its tar. But the worn and gears are so worn that no matter how much i lower them they will bottom out before they tighten up the backlash. The "original" binding turned out not to be binding after all, it was a bad encoder. I found it by mistake, when I turned the drive to open loop to get it to the top of the shaft to hang the car again, the bucking went way. Grabbed an encoder from a car being updated around town and she runs great. Other crews not happy they have to run on open loop but they will live. I still can't figure out why I have no wipe in the down direction. I did check the balance of the car , it is way off. The car wants to drift down rather then up even at the top of the shaft. I told the guys who will be replacing it that I want the machine when it comes out so i can play woth it more to figure out what the heck is going on with the lack of wipe in the down.
I'm thinking there's no wipe in the down direction due to the weight being off, ie car wants to drift down. Since the car wants to drift down empty, it's always got pressure on one side of the teeth. If you run up, it's the same side. If you run down it's probably still wiping on the same side since gravity pulling the car down faster than the machines running the gears.
I bet if you lightened the car up or added weight to the counterweights so the car wanted to drift up empty, you'd see wipe on the opposite side of the teeth
In other words, it sounds like the machine running is "letting" the car run down and the cars still pushing on the gears in the same way, not "driving" the car down using energy to pull it down.
This sounds more like a counterweighted winding drum than a traction. I'm not doubting you, I've just never heard of a traction that the counterweights were lighter than the car. I get concerned when I see cars counterweighted at less than 40% of car capacity plus empty car weight. What brand is it?
I agree with EElevator. If the car weighs hypothetically 1000 lbs. And, the capacity is 1000 lbs, the counterweight should weigh 2800 lbs, at 40%. That would make either the car being way over 2800 lbs, or the counterweight being way under 2800 lbs. not even counting the weight of the ropes with the car at the top level. Something is way out of spec here. Please let us know the final outcome.
The machine is a 1918 Otis #1 , it was modded in the 60s with a cj Anderson controller , and a hack job in the 80s where someone changed the dc motor to AC and added a drive , city has not record tof this work being done . The car is the size of a 4500 # in size but only rated at 1800# , as part of the mod we are doing , we will be replacing everything but the rails and making it a 4,500# car.
