What is preventing the scissor jacks from collapsing?
What is preventing the scissor jacks from collapsing?
(OP)
Hello, I have some questions about the scissor jacks. Is it the friction between the lead screw thread and the two nuts at the front and back sides of the jack? What type of friction is helping the jack to uphold the load to a specified weight without collapsing? Is there a formula? Thanks





RE: What is preventing the scissor jacks from collapsing?
RE: What is preventing the scissor jacks from collapsing?
RE: What is preventing the scissor jacks from collapsing?
RE: What is preventing the scissor jacks from collapsing?
RE: What is preventing the scissor jacks from collapsing?
Lead screws have a lower efficiency than a ball screw which can be used to an advantage to hold a load. Check out some of the technical information by a lead screw company such as Nook. Manual machine tools use lead screws vs. ball screws for the same reason.
Kyle
RE: What is preventing the scissor jacks from collapsing?
https://en.wikipedia.org/wiki/Screw_(simple_machin...
Self locking of a wedge:
https://en.wikipedia.org/wiki/Screw_(simple_machin...
Remember that the angle of a thread face to the axial load is formed both by the included angle of the thread, and also the pitch.
RE: What is preventing the scissor jacks from collapsing?
This means they both have bar sticking out at either end.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: What is preventing the scissor jacks from collapsing?
RE: What is preventing the scissor jacks from collapsing?
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: What is preventing the scissor jacks from collapsing?
so if the rod can't rotate ('cause, say, a pin is engaged in some structure) then the lift position is restrained.
no?
another day in paradise, or is paradise one day closer ?
RE: What is preventing the scissor jacks from collapsing?
Locking depends on both friction and thread helix angle. The critical coefficient of friction equals the tangent of the helix angle. If the coefficient of friction is greater than the critical coefficient, the thread locks the load.
Ted