small lathe job needed

Hi,

I have a motorcycle lift which is not safe to use as it drops very fast. I have narrowed it down to a bent pin in the release mechanism which binds because it is bent. I made a little video to show the run out. I would be happy to make a digital file to show dimensions... .DXF file etc? Happy to pay for time and materials please pm me if you can help! Thanks,

James

Video at

https://vimeo.com/538381882

Hello James,

With it held in the drill chuck, try tapping it straight with a soft famed hammer, or a short length of timber and hammer to chase the run out to something like it should be.

I don't think it will be made in hardened materials and that way you can fix it yourself

Good luck

Brian

A rough location would help, there may be someone close by.

James

Check your mail INBOX on the top line menu.

Emgee

Hi Emgee and all

Thanks v v much Emgee I have been on Fusion 360 yesterday before I read these posts... I have pm'd you back mate. Best wishes

James

Sorry, I am in London (NE)

I am in the Midlands so to far to tie up with a fellow motorcycle tinkerer.

That's ok, Chris... good to be here. Emgee is great, helpng me out. I think we can work through my prob. I hope I can help out myself now I found you guys. I will give you an update when I have made progress.. cheers,

James

Hello All, I made a little video of progress with my motorcycle lift - thank you Emgee for your most excellent help...

https://youtu.be/6Xt4PVKFF74

I have the same bike lift. It has never done that. What i will say is you had no weight on the ramp when trying. It may need adjusting some more so it releases much slower. The only way you would know is with weight on it though. I seem to remember when i 1st got mine & raised it. It would not go back down without any weight on it.

Steve.

Dear Steve

For adjustment I only know you turn left hand screw head clockwise to slow it down. Mine is fully tightened, i.e. closed... is there any other way? And how can I get into release vlave to have a look? (where the ball bearing is)

Presume I have to remove the reservoir first. I'm looking for some online description of disassembling that ram..

Do you mean that I have to put some weight on it and then I will see you the lift lowering more slowly? not sure how that would take place but I will sit tight I suppose ha ha

Thanks for taking the time to reply on this thread I welcome any information of course cheers James

If it lowers too fast with the control valve fully closed, there is leakage, possibly between valve and seat.

Is the control valve coned, bearing directly on the seat, or is it flat ended pushing a ball bearing onto the seat?

Could there be dirt between the valve and the seat? A quick and nasty cure would be to raise the lift, and open the valve wide, in the hope of flushing any debris clear. But no guarantee that the problem won't happen again.

Either way, some attention may bring about an improvement.

Another way to reduce the rate of lowering, would be to drain the oil and replace it with one of higher viscosity.

Howard

Edited By Howard Lewis on 19/05/2021 11:39:16

Hi Howard,

The pin is cone shaped - it lowers into a hole and you can see behind it the ball bearing which is sprung. The end of the pin is flat yes…It is a little bit of a mystery to me the internal structure of this valve. I have looked around for some sort of diagram of how it would work with no results so far.

I did take the time to smooth the surface of the pin as it was extremely rough and badly made. I polished it smooth with wet and dry up to 1000 grit.

Dirt in the system may be a remote possibility but I have drained the oil out and squirted in lots of brake cleaner throughout the internal passages, especially the reducing valve opening...before letting it dry and refilled it with oil when the ram was taken out for examination.

I think you're right though it could be leakage between the valve and seat...

Yesterday I ordered some SAE 46 hydraulic oil and before going any further I will drain the oil and try the more viscous oil. Currently it is filled with Halfords hydraulic jack oil and annoyingly the packaging does not show what viscosity the oil is. I went online and chatted with someone at the other end and their suggestion was to go to the shop and ask them, not very helpful! In other words, I am not even sure if Halfords hydraulic jack oil is SAE 30 or SAE 32.

The SAE 46 oil should arrive tomorrow or the day after and I will try it and report back....

If it is a bad fit between valve and pin would it be an idea to use lapping paste or is that a bad idea?

I really appreciate your suggestions so if you have any further thoughts I would be most grateful to hear them

also, if you know of a decent source for a cross-section drawing of this type of valve I would be really interested too.

cheers,

James

Jack oil will likely be SAE 10, ISO 32. Noel

yes Noel,

you are correct -

sorry, i said SAE 32; I should have said ISO 32, (throughout. interchange SAE with ISO)