Harry - 1997 Tecalemit Twintek Mk3 Hoist

[spunkymonkey]

Ok, seeing as someone asked for photos, I decided to do a thread for Harry the Hoist:


He was bought second hand by the owner of our workshop a few years back and installed as he'd been in his previous home - badly! He also had his 3-phase motor removed and changed for a single phase, which meant he couldn't actually lift anything much heavier than a Reliant Kitten. Well, not strictly true - once moving he'd lift full (2 tonne) load but he wouldn't actually start with any real load applied.

The columns are connected by a chain drive through the base, which is working ok but a little noisy thanks to a missing tensioner spring in one tensioner (the horribly emulsified oil might not help much either!):


That's a fairlyt minor point though, so can wait indefinitely while the rest is sorted!

First job in getting him working again was to learn how 3 phase motor wiring, with reverse and safety interlocks works. Won't bore you with the details but the end result was this:


3 phase motor refitted, with twin (for reversing) contactors and overload cut-out, operating by his original push-buttons. Incidentally, it seems that to reverse a 3 phase motor all you have to do is swap any two of the 3 wires. How cool is that? ;D

The problem at this point was that the top and bottom limit switches weren't working because there's (meant to be) a safety cable that runs from the carriage on the "motor" leg, over a spring-loaded pulley at the top of that leg, down and through the base, then up the slave leg to the other carriage. The cut-out switches are operated by the pulley moving up or down on it's spring mounts. The cable had broken at some point and someone had re-wired to simple limit switches at the top and bottom of the motor column.

That's all well & good but the cable has other uses. Say, for example, you're lowering a car and you've forgotten to move the trestle that's under one lifting arm. As soon as that arm hits the trestle it stops moving down - the arms just rest on the lift nuts, so they have to go up together but when lowering one can be left behind.

That pulls on the cable, which pulls the pulley down and immediately operates the lower limit switch no matter how far off the ground the arms are. So you don't tip the car off sideways by lowering it onto an obstruction.

Also, the lifting nuts have a safety nut fitted underneath them that will "catch" the load if a main nut fails, only allowing it to fall about 10mm. But that 10mm is enough to alter the cable tension and, again, operate the cut-outs so that the hoist can't be (unknowingly) operated with a defective main nut.

Being a little allergic to dropping cars on my head, I decided that he needed a new cable. Convinced his owner to fork out £14 for 30m of 3mm steel rope (a small price to pay for peac of mind!) and started to thread it. Only, it wouldn't feed through the base from the motor side, which meant lowering the leg enough to feed directly into the guide tube. Tipping around 1/4 ton on steel post over at an angle makes me a little nervous, so plenty of straps and an engine crane were employed:


That allowed enough tilt to get my fingers in under the column and start feeding cable through:


Once bolted back together, with new arms fabricated for the limit switches (photos another day), the top switch worked beautifully but the bottom one failed to operate. It was only a matter of adjustment but the failure to stop promptly broke the new cable!

Luckily, it broke very near the end and I haven't trimmed it to length yet, but I couldn't be bothered to re-do it today so called it quits for now. Hopefully, more photos and reports of a working hoist in the next couple of days - then follow-ups will show just what he can do and how easy some things become with Harry on your team ;D

[pauldaf44]

Ooh I know how easy things become with a 2 poster lift as I regularly use them at college. We have 2 different types at college. One like the one you have there and the other an almost new thing with 2 driven posts and no chain. I dont like it because of all the safety crap on it. For instance you cannot lower the lift without first raising it for a second as the safety locks wont disengage. Ruddy hatefull thing

[spunkymonkey]

I'm not a great fan of 2 posters anyway because they're inherently dangerous compared to 4 posters. I'd rather lose a little access with a 4 post than use a 2, but it's a case of what's there is there and may as well make the best of it!

Seen more than enough safety investigation reports from cars falling off them, usually with someone underneath! Don't forget, with only 2 posts, if one fails the whole thing fails, if a pad slips because you pull too hard on something you're undoing or shake it too much, the whole thing fails, if the car is too rusty around one pad, the whole thing fails. And if the whole thing fails, the car falls off it.

So any extra safety features are fine by me!

[Bob Scrivens]

It normally a safety feature on these type of lifts, if they are stop on the way down they will only start in the up direction.
Its to try and stop a crushing or shearing incident.
Is it 3mm air-cord cable you need Joe?

Bob

[spunkymonkey]

It is, Bob, but I'd cut about 3 metres over length to be sure I wasn't short (had no pattern to follow and a lot of the run is invisible in the base) so there's plenty to pull through and re-secure. When it's all set up correctly it doesn't carry any load as such - just the spring pressure of the switching - so I'm not too worried about the shock loading it took either.

In fact, it's reassuring to know that failure did what it was meant to and disabled the raise direction while still allowing it to be lowered

[33grinder]

Great stuff Joe!

It's amazing the difference a lift makes so you can work at a decent hight under a car without having to scrabble around on your back.

I'm very fortunate that Island Landrovers has a four poster with ramps, albeit that is not without problems as Gavina is a tight fit with her narrow track.

I guess it's all a compromise really whatever set up you go for. I do remember a few years ago using a wonderfull hydraulic lift. Drive onto ramps (floor level, embeded into the concrete floor) and it would raise through a central post. Once off the ground the ramp could be rotated through 360 degrees - very handy but also a worry with (seemingly) no inherent safety features..

[Bob Scrivens]

Ahh the hydraulic ones have a device called a rupture valve fitted to the base of the hydraulic cylinder, if a pipe burst's or hydraulic pressure was rapidly lost, this device would close off the cylinder and can only be released by applying hydraulic pressure back to support the load.
Joe you may find a switch some where on the chains, where if they go slack if the hoist encounters an obstruction when lowering should stop the hoist and only allow upward movement.

Bob

[spunkymonkey]

That's all controlled by the cable on this one, Bob.

It's a rolled screw on each post, the motor turns one and the chain drives across the base to the other. The screws each carry two nuts, joined by a 5mm pin but set with a couple of threads gap between them. The carriages sit unrestrained on top of the nuts.

The cable runs from the bottom of the "master" carriage, down through a guide on the main nut that side, then up over a pulley at the top, down again, through the base, and is attached to the opposite carriage. The limit / safety switches are operated by movement of the pulley, which is normally pulled down slightly (it's on spring mounts) by tension in the cable.

When the master carriage reaches the top, it physically pushes the pulley up on it's spring mounts and operates the top limit switch. If the cable breaks or becomes slack, it releases the tension on the pulley and allows it to spring up, disabling "up" movement via the limit switch.

When the lift reaches the bottom, the carriages stop but the nuts continue to move down for a few turns. This increases tension in the cable because it runs through one of the nuts, which pulls the pulley down fully on it's mount and operates the lower limit switch. If a carriage is obstructed the same thing happens.

It's a really neat and simple system once it's set up but setting it up is proving to be a slight PITA seeing as it was missing the operating levers for the limit switches - bodging replacements that are accurate enough and reliable is proving a little challenging because you can only test the bottom one by winding it down and, if it doesn't cut out, it puts too much strain on the cable and something gives!

I think I'm just about there now, will know if it still does what it should tomorrow

[spunkymonkey]

Got to test Harry today using Sheila as a guinea pig. At about 950kg she's about half the rated capacity and, being off road for now, it wouldn't be the end of the world if she was dropped. So got her positioned:


Raised her clear of the ground for a stability check (shake like crazy and make sure she stays there ):


Then up she went!


I really don't like the way cars seem to rock / bounce on these 2 posters, but she seemed secure so it was time to poke around a bit.

Once I got over the "don't trust 2 posters" bit, it was so nice to be doing this standing upright! Started with the small hole in the o/s sill:


And checked to see how big it really was. Oops!


On the plus side, it's a completely flat area along there, and the inner membrane panel is sound:


so not too difficult to patch up neatly

Then it was a quick check round the wheel bearings - without having to stop and jack up each corner in turn. Luxury! The results were, both n/s are fine (but there's some play in the n/s inner track-rod joint), o/s/r needs adjusting and o/s/f needs checking for either adjustment (re-shimming) or replacement.

Brake pipes were next on the list. I was aware of this rusty bit on the main front / rear pipe:


But not this bit:


That second bit is actually worse than the rear, so one brake pipe to replace.

Then it was round the various known trouble spots round subframe mounts. Rear n/s, center and o/s are all sound but could all do with a bit of fresh protection to keep them that way:






Fronts are also ok, with plenty of oil protecting the n/s chassis leg and some surface grot on the o/s:




The front subframe front mounts are basically sound:




but there is some rot on the o/s inner wing / chassis extension in that area:




There are also two dead balljoint gaiters (not a fail yet but need sorting given the price of balljoints), a hole in the downpipe, and a stale donut:








So, all in all, nowhere near as bad as she could be and all stuff that can be sorted for a few hours work and minimal expense

Time to dig out Sheila's thread again I guess.... ;D

[spunkymonkey]

;D Original Metalastic ones were ok - and they do provide good cushioning for the drive train (hence the almost infinite CV joint life on these) - but they cost between about £90 and £180 a side now and are (at least) 20 year old rubber. The "other make" ones are around 1/4 the price but don't last anything like as long, especially with oil contamination.


I wonder if polyurethane ones would work???

[33grinder]

Well done Joe! Glad to hear Harry is back in working order.

Shiela should only make an afternoon's work for you Joe, or a couple of weeks for a full resto... ;D

Certainly makes work a lot more pleasant when you can adapt the hight of your work to suit your ease and comfort, rather than contort yourself and jacks and stands, on your back straining on a rounded nut whilst your hair acts as a mop for the workshop's spilt oil and sawdust.