Vintage car lift

[Nicks garage]

Hi all,, not been on here for a while to be honest I forgot it existed, but then remembered what fountain of knowledge everybody has
I have an issue with my car lift. It’s a three phase Hoffman single post converted to 240 V single phase with capacitors. I’ve decided to get an inverter to take it back to three face to give it more power so I have stripped the lift down and found a potential issue. Somebody has welded a tab onto the lift nut and clearly removed some sort of sensor. I’m just wondering what I need to take it back to standard. I do have another stripped lift for parts that doesn’t have this welded on section but doesn’t have a switch either or controller and help is massively appreciated. I can’t find anything online.

 

[cpakalolo]

15 years ago, I used to put a freq. drive on anything. Using them to make 3 phase for a lift pump would be one of those applications. If you program them with wide ranges, they will work quite well with a lift pump that only has a 8 percent duty cycle. Don't program overloads or soft start for the best results.

 

[djbmw]

Hi all,, not been on here for a while to be honest I forgot it existed, but then remembered what fountain of knowledge everybody has
I have an issue with my car lift. It’s a three phase Hoffman single post converted to 240 V single phase with capacitors. I’ve decided to get an inverter to take it back to three face to give it more power so I have stripped the lift down and found a potential issue. Somebody has welded a tab onto the lift nut and clearly removed some sort of sensor. I’m just wondering what I need to take it back to standard. I do have another stripped lift for parts that doesn’t have this welded on section but doesn’t have a switch either or controller and help is massively appreciated. I can’t find anything online.

Ah yes... the Duolift.
The lift nut and jam nut, when worn down, can occasionally jam - leaving a car stuck up in the air. There's supposed to be a cover on those nuts with a circle that you can stick a screw driver or punch through... but it looks like you removed it? Anyway, if the two get jammed (like double nutting a bolt), you need to pound them apart with a punch or screwdriver and hammer. Someone welded on massive tabs to make it easier. On my duolift 6500 (that I sent to the scrap heap), i had drilled indentations that I could rest a punch on.

As for the sensors... on mine there were two microswitches. One would trigger when the lift was at max height, cutting power to the motor, and another would do the same when the lift trolley was at the bottom.

Edit: i know yours is a single post lift but the screw, lift nut, and jam nut assembly is likely the same. There's schematics online that detail the nut orientation and binding issues. If i find the copy I have, I will upload it.

 

[cpakalolo]

I haven't seen a screw lift still working and I don't think I would keep one. If it wasn't used outside, and wasn't used in a gritty environment it could be good. The one you have doesn't look it has much life left. If the acme threads get worn, they will jam more. Once you get 2 or more times with a car up high, you will probably throw it away. For now, it is something that you want to repair. Good luck finding anything for it. I'm just warning you of the difficulty in your quest. One in which you will have to make your own parts. A few years ago, I tented one and power washed it to reveal that it wasn't worth fixing. I did all the research to find parts and was going to put a couple days into rebuilding it so I would have a friend with a lift that I could borrow. When he saw the work that would go into it, he took a picture and listed it on Ebay. I looked for used lifts this spring to save money and was severely disappointed in what I found. I ended up buying a new one because parts just don't exist. The designs have settled down and are pretty consistent on new models of lifts. The direct drive cylinders that pull rather than push are the most reliable so far. I was looking at chinesium 11,000 lb lifts for a 12 ft ceiling and I chose a Tuxedo open floor Assymetrical, single point lock released model. If I wanted to go with Katool, I was going to do a 12,000+ lb model to get a stiffer post and arms for less flexing under load. I balked on it because I think going under the vehicle to hit the lock releases was a no starter. I also wanted Assymetric arms just in case. I haven't put it up yet because I am still building a 3 foot extension to my ceiling height with trusses. I hope the whole job doesn't cost over 9 grand, I'm close. The lift delivered was about 4000 bucks; the lumber is killing me. I wanted an ALI rated lift, but I figured I would be best served by a non ALI lift for my needs. Companies cannot even converse about modifications to an ALI lift. The certification leaves when you do any modification at all. Even if you drill a hole to screw in a bracket for holding wire or conduit, the certification leaves. I am capable of judging whether something is strong enough to stand under, I hope. Eventually, I will cut it into a few pieces to make something better for storage where I can swing the post in the middle of the garage out of the way. I may not. I went with the expensive Hilti anchors that are bolted into, leaving the floor clear after removal. I know there must be other people that modify lifts and aren't afraid. On the farm we modify everything out of necessity.

 

[djbmw]

I haven't seen a screw lift still working and I don't think I would keep one. If it wasn't used outside, and wasn't used in a gritty environment it could be good. The one you have doesn't look it has much life left. If the acme threads get worn, they will jam more. Once you get 2 or more times with a car up high, you will probably throw it away. For now, it is something that you want to repair. Good luck finding anything for it. I'm just warning you of the difficulty in your quest. One in which you will have to make your own parts. A few years ago, I tented one and power washed it to reveal that it wasn't worth fixing. I did all the research to find parts and was going to put a couple days into rebuilding it so I would have a friend with a lift that I could borrow. When he saw the work that would go into it, he took a picture and listed it on Ebay. I looked for used lifts this spring to save money and was severely disappointed in what I found. I ended up buying a new one because parts just don't exist. The designs have settled down and are pretty consistent on new models of lifts. The direct drive cylinders that pull rather than push are the most reliable so far. I was looking at chinesium 11,000 lb lifts for a 12 ft ceiling and I chose a Tuxedo open floor Assymetrical, single point lock released model. If I wanted to go with Katool, I was going to do a 12,000+ lb model to get a stiffer post and arms for less flexing under load. I balked on it because I think going under the vehicle to hit the lock releases was a no starter. I also wanted Assymetric arms just in case. I haven't put it up yet because I am still building a 3 foot extension to my ceiling height with trusses. I hope the whole job doesn't cost over 9 grand, I'm close. The lift delivered was about 4000 bucks; the lumber is killing me. I wanted an ALI rated lift, but I figured I would be best served by a non ALI lift for my needs. Companies cannot even converse about modifications to an ALI lift. The certification leaves when you do any modification at all. Even if you drill a hole to screw in a bracket for holding wire or conduit, the certification leaves. I am capable of judging whether something is strong enough to stand under, I hope. Eventually, I will cut it into a few pieces to make something better for storage where I can swing the post in the middle of the garage out of the way. I may not. I went with the expensive Hilti anchors that are bolted into, leaving the floor clear after removal. I know there must be other people that modify lifts and aren't afraid. On the farm we modify everything out of necessity.

I also agree that screw-type lifts are a major PITA - and you should start planning on upgrading to a hydraulic one. Having said that, I edited my post above with clearance measurements. Usually, these will never change. However, if the sensor for "max down" has failed, you could easily force the trolley into the ground and strip the lower threads. Doing this results in the two nuts getting out of spec, resulting in a jam while in use.

 

[cpakalolo]

I also agree that screw-type lifts are a major PITA - and you should start planning on upgrading to a hydraulic one. Having said that, I edited my post above with clearance measurements. Usually, these will never change. However, if the sensor for "max down" has failed, you could easily force the trolley into the ground and strip the lower threads. Doing this results in the two nuts getting out of spec, resulting in a jam while in use.

I am also a "fix anything" kinda guy. So, me saying get rid of it is rare. I wanted to comment on the lower threads. Yes, the lower threads get worn more. This is why eventually the jam nut doesn't work any more. The jam nut is to take up the slack to the threads. By mis-aligning the nuts on the threads, it takes up tolerance space and makes a tight action. Kinda like a double screw crescent wrench. If the threads are worn more on a portion of the threads, the jam nut will be too tight on the good threads and loose on the worn ones. Now you have no ability to take up the slack. It jams. Now, one could put a tack weld where you could break it if needed, but it won't spin the loose nut. It would be a trade-off and it would possibly make it worse if your screwshaft is worn. You can buy those limit switches off e-bay; they aren't anything special. You will need to remove those extra pieces that were welded in by the previous owner. I can't even remember how it should be as I have only seen three of them in my life and my boss didn't like working on them at all. It wasn't in our flat rate pricing books, so we had to charge hourly. I am no expert at all on these things either. It's just that there aren't many of them out there and most are completely worn out.

 

[djbmw]

I am also a "fix anything" kinda guy. So, me saying get rid of it is rare. I wanted to comment on the lower threads. Yes, the lower threads get worn more. This is why eventually the jam nut doesn't work any more. The jam nut is to take up the slack to the threads. By mis-aligning the nuts on the threads, it takes up tolerance space and makes a tight action. Kinda like a double screw crescent wrench. If the threads are worn more on a portion of the threads, the jam nut will be too tight on the good threads and loose on the worn ones. Now you have no ability to take up the slack. It jams. Now, one could put a tack weld where you could break it if needed, but it won't spin the loose nut. It would be a trade-off and it would possibly make it worse if your screwshaft is worn. You can buy those limit switches off e-bay; they aren't anything special. You will need to remove those extra pieces that were welded in by the previous owner. I can't even remember how it should be as I have only seen three of them in my life and my boss didn't like working on them at all. It wasn't in our flat rate pricing books, so we had to charge hourly. I am no expert at all on these things either. It's just that there aren't many of them out there and most are completely worn out.

I owned a Duolift 6500 (screw drive),.. and it worked OK for years on cars and light weight vehicles. As soon as I started lifting heavier vehicles, it began to jam and stall all the time. This ended up being the straw that broke the camels back, and I ended up taking the lift to the scrap yard after 12 years of ownership.

Thus far, my 10k hydraulic lift has been a dream and easily lifts loads that the hofmann lift would struggle with.

 

[mikedodge]

It looks like you've already got your answer.

The nut and some of those parts that run up and down the shaft wear out from time to time and need to be replaced. It looks like someone was trying to compensate for worn out parts to get some more life out of it.

Those Hoffmans in 2 post form were the first hoists I ever used and I like them for the simplicity of how they work and the short columns. But swems like they can be a nightmare to fix when they have those problems. I saw one last year I would gave been interested in but someone did some funky mods to it and looked they never had it working. I've seen it for sale once or twice since.