2 post ramp - lift nuts

[grim_d]

A friend and I have bought an old Imola/Harlem 2 post ramp which required new main and safety nuts, it is quickly becoming clear that the ramp and therefore the nuts are obsolete so may be looking into the possibility of having some made.

It seems that it has had a combination of old style and newer style nuts fitted, working on the basis that the main nuts wear quicker than the safety nuts I am assuming that the older style is what I am after.

I have attached a picture of the nuts, the one on the left is probably the type required.i don't currently know the thread.

I know it is quite vague but I'm curious if it might be financially viable to have some made or just to weigh in the ramp.

Anyone ever had this done before?

The nut pictured below had to be cut off the screw as it had jammed due to wear, that;s why there are slits up the side.

 

[AndyStobbs]

Think it will come down to how good/bad the rest of the lift is, when a half decent second hand two poster can be had for well under £1000 you need to be looking at the screws themselves, the bearings, the arms.
If its going into work premises then its LOLER, though that said the amount of garages I go into who don't even have any rubber on the lift pads is worrying.

can't see you getting two lift nuts made for less than £300 a pair. Safety nuts are steel and just square in profile I'm guessing which is much less work.

 

[grim_d]

The rest of the ramp seems to be in good order for the most part, having had new top bearings and drive belts recently, screws are fine, bit of runout on one but nothing that concerns me. We picked this up for £290 delivered so were not hugely out of pocket yet. We are keen to keep it as it is an old chain and screw type rather than cables/hydraulics.

Ramps can be had under £1000 as you say but with any second hand lift I would be looking at replacing lift/safety nuts/cables in any event.

After some investigation it appears that both nut types are used on the ramp, as it it physically impossible to install the bigger type first., in this case the safety nuts are also bronze and are installed below a lever which will engage a lock at the bottom of the ramp in the event that the ramp is running on the safety nuts. Note the above picture is just one side of nuts, there are 4 nuts in total.
This particular ramp had both locks disabled and was running entirely on the safety nuts, one of which was won down, and it was in a work premises. We are looking at using it for hobby use.

The hardest part here is identifying whether the power screw thread is ACME or metric trapezoidal, I don't have the equipment available to measure the angle of the thread.

 

[I'm getting on a bit]

It's unlikely a responsible person would make these as liability for accidents

 

[grim_d]

There is a company in the Netherlands which specialises in trapezoidal threads and custom lift nuts, but communication has been interesting.

I dont see how having these made make anyone liable for accidents (home use) or indeed increases the risk of failure.

 

[Onoff]

Don't know if the Unimec site will assist. We've used them at work for lift table jacks:

http://www.unimec.eu/trapezoidal-screw-jacks.htm

 

[AndyStobbs]

can you not measure the thread? to determine the thread form.

Ie. width at root, width at OD, depth of thread, use trig, calculate the angle and determine thread that way against known specifications?

 

[grim_d]

There is only 1 degree in angle between a Acme and metric trapezoidal thread form, I dont think I can accurately determine which is which over a depth of 3mm.

Apparantly I need to use an optical comparator or have a specific thread gauge.

http://www.roton.com/identify_threads.aspx

 

[AndyStobbs]

I know I haven't got it infront of me so forgive me if I am over simplifying, but wont the OD give it away as metric/ imperial?

At 1 degree over less than 1/4" depth of thread I don't think it'll matter which you go with. Its not like those nuts are made for a precision fit. Normal clearance will probably allow interchangabilty in metric/imperial thread form.

 

[grim_d]

I don't know enough about them to say, ive tried looking at some tables but to no avail.

Major diameter is 38.80mm. And minor is 35.80, 3.00mm thread depth.

 

[gaz_moose]

there is a company on ebay who specialise in these load nuts. when they went on my old ramp I just sent the guy a picture of them and he knew exactly what they were off.maybe its worth asking him.

 

[ford34/2]

Might be worth a try:: same company on both links
http://www.ebay.co.uk/sch/automotiv..._DefaultDomain_3&rt=nc&_trksid=p2047675.l2562

http://www.ebay.co.uk/usr/automotive-lift-services

or website:
https://www.automotiveliftservices.co.uk/

Stan

 

[grim_d]

I tried to contact the above some time ago but emailed just bounced back, I will try them through ebay.