Gallery, Projects and General > Project Logs
Motorbike Lift Bench
one_rod:
--- Quote from: Biggles on December 08, 2016, 12:12:10 AM ---Looking at the design of the piston anchor on your frame and wondering if it would be better welded on the inner surface of the cross member so that the strain is taken by the cross member and the side plates instead of the just the welding of the side plates. Just a thought! :coffee:
--- End quote ---
If I'm understanding you question correctly, then it works like this. (I think :scratch:)
In the fully-down position, the ram body pivot, the piston pivot and the bottom pivot of the arm would be almost in a straight line. So when you started to lift, a large proportion of the ram force would go into simply trying to bend the cross member instead of lifting the load.
By offsetting the top pivot in that way it "breaks the angle" and turns the pushing force from the ram into a turning moment around the arm's bottom pivot. The alternative would be to stop the table going low enough to line up the three points, which makes it a little more difficult to get a heavy bike on board.
You're right in what you are saying, about it being less than ideal from a structural point of view at that point, but it was a compromise I'm willing to make to get the loading height as low as possible.
Hope that all makes sense?
vintageandclassicrepairs:
Hi,
--- Quote ---If I'm understanding you question correctly, then it works like this. (I think :scratch:)
In the fully-down position, the ram body pivot, the piston pivot and the bottom pivot of the arm would be almost in a straight line. So when you started to lift, a large proportion of the ram force would go into simply trying to bend the cross member instead of lifting the load.
By offsetting the top pivot in that way it "breaks the angle" and turns the pushing force from the ram into a turning moment around the arm's bottom pivot. The alternative would be to stop the table going low enough to line up the three points, which makes it a little more difficult to get a heavy bike on board.
You're right in what you are saying, about it being less than ideal from a structural point of view at that point, but it was a compromise I'm willing to make to get the loading height as low as possible.
--- End quote ---
I think that while the lift may work as it is, it will struggle or fail when a bikes weight is on it
Adding a set of maybe 2in. pieces between top and bottom platforms would help
The working angle of the ram means that lift per pump stroke is at its maximum when the lift is in the down position
With a a ramp on the end of the lift a couple of more inches will not hurt too much
It would be wise to also fit a mechanical lock to prevent the lift platform resting on the hydraulic ram when in the raised position
I made my own "scissors" type lift and used a trolley jack to operate it, I keep meaning to go and redesign the lifting mechanism and use something like an acme screw ???
My second bike bench is made from an old hospital bed , hydraulics already in place :scratch:
2 cents worth
John
SwarfnStuff:
John
Ha, Very appropriate "My second bike bench is made from an old hospital bed , hydraulics already in place".
After all, these lifts are for "sick" bikes are they not? At least one needing some (medical) :lol: intervention.
John B
Biggles:
Oh very good SwarfnStuff :Doh:
one_rod:
So, after the Christmas hiatus, a bout of Royal Flu (or whatever they are calling the latest mucus-fest) and some unreasonable overtime demands at work, life's finally getting back to normal.
Time to resume my headlong plunge into the world of hillbilly fabrication...
Outrigger / stabilisers
Pretty sure that after I've tripped over them twenty times I'll remember they are there.
Anti-Fallback Mechanism.
Drilled some holes. Like you do.
Guess that if this doesn't work, I could always take up spear fishing.
Drill, weld, grind, weld, drill, grind...
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Can see where this is going now.
Overview.
Starting to look like it might be something? One day.
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