[SOLVED] Electric hoist stops only when going down

[whitediamond642]

TLDR. My electric cable hoist no longer lowers a load more that 18 inches before it goes "dead."

Happy New Year! First time poster and long time lurker. I've always found answers just by searching but do need help with my current issue with my electric hoist that I use as a freight "elevator" from my garage to my attic.

The elevator platform is 3'x5' and weighs around 100lbs. It has trolleys attached that slide along 2 unistrut rails bolted to joists in the wall. The entire platform is raised and lowered by the hoist (Harbor Freight 1320lb model) and has 2 safety cables as backup in case there is ever a hoist failure. The total lift is around 14 ft and the heaviest total load is around 500 lbs.

The hoist pendant was replaced by a Gama Electronics hoist remote control on the platform to allow remote control or direct control while on the platform. The pendant wiring goes through two retractable extension cords that I removed the ratcheting mechanisms from to allow free retraction both up and down. I've had this setup for about 4 1/2 years with no issues.

The issue is that the platform is in the up position in the attic (stored state) and will not lower more than 18 inches before the hoist stops working completely. There is no up or down, no motor hum, nothing once it gets to that point. If I unplug the hoist and let it sit for 5 minutes or so, I can raise it back up. I can raise/lower the platform as much as I want between the top and 18 inch lowered position but as soon as I get to the 18 inches, the same thing happens.

Here's what I have tested:
1. Tested for continuity between the hoist plug, hoist wiring and pendant switch for line/neutral/ground in both the up and 18 inch stop states and all is good
2. Inspected all wiring at the pendant to retractable extension cord reels and associated junction boxes and Gama Electronics remote box and all wiring was good
3. Inspected and tested all three hoist capacitors with a multimeter as good
4. Inspected both safety cables to ensure they are not prematurely engaging
5. Let out the hoist cable to about 36 inches to check for cable binding on the drum. I did this by engaging the safety cables to support the load from the platform
6. Tested both the upper and lower limit switches and wiring. The upper is part of the hoist while I added the lower to the bottom of one of the unistrut rails. All tested good
7. Inspected the hoist for any sign of wear and only found a small drop of oil from the bottom of the hoist

After all the testing, all I can think of is that there may have been an internal failure of hoist braking system keeping it from lowering under load, but that's a complete guess. If I have to open the hoist up, I will likely just replace it with a new one. I'm not even sure what to look for on the braking wear/failure issue and am just looking for advice. I would like to find a better hoist than the harbor freight one if the life expectancy is only 4 1/2 years but also don't want to spend an arm and a leg to do so.

I've added pictures of the setup for some clarification.

 

[Gutman]

Following, as I have a couple of those HF hoists of different capacities, including the 1320.
Is the stopping point consistently the same? If yes, it might point to mechanical. If no, probably electrical.
Are you able to reposition the platform independent from the hoist, to see if it would function normally when reconnected below/beyond the 18"?
Nice setup, btw.

ETA: I looked at a lot of this style of hoist in the same price range (HF, Northern Tool, Vevor, Amazon) and I surmise they're all made by the same kid in chyna, so quality is probably the same, more of a hit or miss. Mine have worked when I needed them, but may not be used as frequently as yours. Idk.

 

[Codyboy]

Wow this is crazy. I lay in bed last night for 2 hours thinking how can I build an elevator for the shop loft.
I have the same hoist but I think mine is 750/1500.
Are you sure the safety stop for top dead center is not accidentally engaging?
Is the motor getting too hot to the touch?
Does everything that should have power still have power once it drops that initial 18" ?

Eta.
No pulleys are binding. That bottom pulley seems really small.
But if hung up I wouldn't think it would cause the cable from unwinding though.

 

[Codyboy]

Hmm. I see it only has a 2 minute on 8 minute rest.
Idk. How that is established on the motor.
Thermal switch maybe? Someone here will know.

 

[My Old Tools]

I chased a similar problem in my 1 ton. I even replaced it with a new one. It was the extension cord on the pendant all along. The connector on one end would make or break the connection at different points based on vibration, twist in the cord, or nothing at all. And yes, I checked many times. ZIt wasn't obvious until I started pulling connectors.

 

[whitediamond642]

Gutman - The stopping point is exactly the same every time. Even if I raise and lower it a bit multiple times before dropping it to the 18 inches where it stops. Repositioning the platform is possible and likely my next step from a troubleshooting perspective if I don't identify another potential culprit. I REALLY like the setup, so trying to avoid having to do any major changes if I can. The current hoist install is already pretty tight but I may look into a different/higher quality one when it comes time.

Codyboy - Feel free to copy anything in my design and let me know if additional pics would help. The limit switch at the top is definitely not engaging, but I'll likely check again before any major changes just to be sure. The top limit switch should still allow downward movement anyway which is why I checked the bottom limit switch, too. The fact that it stops at the same spot every time leads me to believe it's mechanical more than electrical, but I'll still verify one more time before swapping the hoist with a new one. The motor is definitely not hot at all, so I don't think it's tripping the internal thermal protection. Based on my testing, everything that should have power does at both the top and 18" failure positions, which leads me to the mechanical side. I'll check the lower pulley as soon as I get the chance, as I have it covered by the 3" PVC pipe to prevent anything from being caught in it, but it's possible something could have fallen into it. I didn't see any abnormal wear on the cable though.

My Old Tools - This is a likely culprit I will look into, as the retractable cord reels could be a failure point and would have the same failure at the same point each time. That will be easy to test as well since I can pull out the extension cables while monitoring continuity without having to worry about live electrical or the platform moving. I could also see a scenario where a sudden loss of line/neutral/ground while in use might cause some sort of internal safety protection to engage(?). This is likely where I'll start before replacing the hoist.

Thank you all for the discussion and ideas here! Very much appreciated!

 

[whitediamond642]

Also, I used the same cord reels for my garage door lighting solution to maintain ceiling lighting with the garage doors are open during the hot KS summer evenings. The reels get used everything time the garage doors open and I've had zero issues there. Still, this would be a much easier (and cheaper) issue than the hoist itself.

 

[matt_i]

I would pigtail out some wires or use alligator clips to measure AC voltage on the hoist motor to make sure you are sending 120vac at the times you think you are.

The continuity is a good start but sometimes "weak" aka high resistance electrical connections can mask a problem.

The cord reels are relying on sort of a slip-ring, this could also have a bad spot.

It would be good to review your wiring diagram...I am picturing you have overtravel limit switches with normally closed contacts, the upper switch - NC should be in series with the UP function and the lower switch- NC in series with the DOWN function.

That you can't go up or down at the 18" point suggests to me either the transmission has a problem internally, or that you lost AC power for the "COMMON" terminal somewhere.

 

[Codyboy]

.

Very informative!
Will take a while decipher all that info.

 

[matt_i]

Sorry, I rewrote. I didn't find the Delete function otherwise I would have used that.

 

[Codyboy]

Sorry, I rewrote. I didn't find the Delete function otherwise I would have used that.

Yes. I figured as much. I haven't found that button either. I'll so.etimes just back out of it or type "dupe" or "nm"

Dear GJ,
Can we get a cancel button on the text box?

 

[whitediamond642]

Hey all. I just got home from a trip and was able to do some additional testing. The issue is with the left retractabke cord reel. As soon as I gave it a tug to get past the 18 inch failure point, the hoist started working again!

I'm not sure what the connection issue is, but matt_i is right that despite the continuity test succeeding, there must be enough of a connection issue for there to be a voltage drop at the motor. I thought I had tested that at the 18 inch stop but clearly not.

I will replace that real with another. Disassembly of those and rewinding the retraction spring is a HUGE pain but not nearly what it would be if I had jumped straight to replacing the hoist only to have it not fix the problem.

For now, I have a temp fix and can get to my attic workspace if needed. I REALLY appreciate everyone's input and advice here!

 

[mm08822]

Hmm. I see it only has a 2 minute on 8 minute rest.
Idk. How that is established on the motor.
Thermal switch maybe? Someone here will know.

Unfortunately, the onus is on the user to abide by that 25% duty cycle. I would also expect it varies based upon the actual load and direction. 25% is probably for raising max load.

I hope there is some type of thermal protection, too. Relying on that too often could still fry the motor.

 

[whitediamond642]

I would say I use it at least 4-5 a week on average throughout the year. Definitely more during summer during prime project time periods. I've never timed the total travel, but I would estimate around 30 seconds one way, so I would rarely hit the max duty cycle. Even if I do, it's far below max load. The most I put on it is my engine hoist and myself, so around 500lbs max including the platform. I'm hoping to get at least 10 years before I have to do anything major to it. This is literally the first problem I've had (knock on wood!) I just ordered a replacement reel for delivery tomorrow (gotta love Amazon), so it should be back in action shortly after.