Scissor Lift Design
Scissor Lift Design
(OP)
Hello All,
I am looking for some kind of supporting solution/ idea for already designed and manufactured scissor lift. We have manufactured scissor lift for our workshop use only. It can lift the load well up to certain limit. When we try yo lift some heavy load, it lifts but not without deflections of the arms. This way it has also hard time to move up unsupported end side as shown in image.
In future we will re engineering it again but for now we are looking for some kind of linkage mechanism or other idea to support the unsupported end go ahead.
Thank you
I am looking for some kind of supporting solution/ idea for already designed and manufactured scissor lift. We have manufactured scissor lift for our workshop use only. It can lift the load well up to certain limit. When we try yo lift some heavy load, it lifts but not without deflections of the arms. This way it has also hard time to move up unsupported end side as shown in image.
In future we will re engineering it again but for now we are looking for some kind of linkage mechanism or other idea to support the unsupported end go ahead.
Thank you





RE: Scissor Lift Design
Is this a commercially available lift? By how much are you exceeding its load raring?
Using it beyond it's rated load is looking for trouble, maybe even fatalities.
Is this a one time situation, or will you be handling these heavy loads routinely?
Increasing the "I" moment of Inertial of the "arms" will reduce the deflection, and prevent deformation.
But the strength of all the pivoting joints, and even the limits of the lifting cylinder may be exceeded too.
RE: Scissor Lift Design
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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RE: Scissor Lift Design
When I look the other way around if I can support the unsupported end, it will be more efficient as there will be more transfer of load to all the joints. We might lift heavy load twice or thrice a week.
What happened here is that we have to lift wide load from low ground level. We are not scissor lift manufacturing experts but we decided to do all by ourselves. It ended up selecting long arms(thus reducing mechanical advantage).
Just want to find solution before permanent deformation of beam or damaged pivot pins.
RE: Scissor Lift Design
RE: Scissor Lift Design
RE: Scissor Lift Design
People get killed when stuff like this collapses or falls over. Buy one that's certified for the load you are trying to lift, and follow the information for use that is supplied with it.
RE: Scissor Lift Design
Why do you think that won't work?
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: Scissor Lift Design
The safety of your lift is highly questionable if you can see the tilt in the platform.
RE: Scissor Lift Design
Ted
RE: Scissor Lift Design
IR Stuff : My point is that currently I have two points to transfer the load to base as one is free and other end is supported. If I can support free end, it would be more efficient way to transfer the load.
Compositepro : Yes, I agree with you that it has stiffness problem, but I believe that it just need some support to transfer the load as I see all the time how it goes when we lift the load.
Hydtools : You are right. I was thinking the same way that just mirror one cylinder on the opposite which is not supported. It will good to go. It will synchronize with the movement of exiting two cylinders in parallel circuit. To be honest I was trying to visualize some kind of linkage mechanism which can synchronize with cylinders while they move upward (lift) and downward (gravity down).
RE: Scissor Lift Design
RE: Scissor Lift Design
Huh? If your load was within limits, the scissor would work correctly, and works still, since nothing has fallen or broken or permanently deformed. Therefore, the correct answer is to make the original design stronger, not come up with make-shift patches that might make things worse.
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: Scissor Lift Design
you could just position the platform so that the mass center of the heavy load is near to the cylinder side.
RE: Scissor Lift Design
CostaV : The platform has function of pushing the load, so even if I set the mass center of heavy of near the base of the cylinder, it has to move forward. towards unsupported ends.
RE: Scissor Lift Design
Worker safety is clearly at risk.
This is unacceptable
Take a big step back and make sure the "way it has always been done" is acceptable
At the very least, dig up the old design work and interview the people responsible for the existing machine.
Research and find the codes that apply, including OSHA
Define the current static and dynamic loads for all operating conditions
Include fatigue if appropriate
Establish safety factors
Review the current machine and establish safe static and dynamic loads
Stencil those on the machine
Look at "what-ifs" like hydraulic power loss, external forces or impacts, etc to make sure it is still safe
Investigate control systems to cut power or otherwise disable or lock the unit if the design load is exceeded, power fails, the load is off-center, etc
Put it all in writing
Then
Define the new static and dynamic loads for all operating conditions
Design a new or modified system for the new loads
Review all high stress areas, often at the joints
Examine one you can buy to see where you went wrong
Iterate
Your first priority is worker safety
You've been lucky so far but now an engineer is involved and luck ain't good enough any more
It sounds like your company's home-made system is exceeding its (unknown) capacity and putting people at risk
This is your chance to draw a line in the sand and as an engineer take a principled stand against ignorance and possibly stupidity plus protecting your company from a preventable accident
My opinion only, from a cranky old engineer...
RE: Scissor Lift Design
(1) You know it has been tested and retested by both the manufacturer and numerous other customers.
(2) It comes with a tested, verified, certified, and labeled load limit.
(2) It comes with a warranty.
(3) The vendor legally assumes some or all of the liability in case of failure.
(4) If there is a failure, your business is not the only one at risk.
Realistically you are not saving any money building (and rebuilding) this thing yourself. Just because you have some tools and materials is no reason put your employees, and your business, at risk.
Please, please give it up and do this thing right.
RE: Scissor Lift Design
If you have completed an analysis then you know the safe load limit of the lift (and it should be clearly marked on the lift so the people operating it know) and the weak points (and so can answer your concern about reinforcing the arms, sending the load to the joints). Then it becomes a "simple" matter to redesign the lift for a higher load, and possibly dual actuators.
another day in paradise, or is paradise one day closer ?