Two rams equalizationgreenspun.com : LUSENET : Elevator Problem Discussion : One Thread
Can someone advice me with different ways of two rams equalization. It's about ropes vehicle elevator which is not balanced from side-to-side. The reason is probably because of different loads on rams. What will be the best way to overcome this problem? What about a direct two ram installation (with no cables)? Thank you David
-- David Touito (firstname.lastname@example.org), March 15, 2004
There are (at least) three ways to equalize multiple jacks.
Mechanically, by using a rope and pulley system that in effect ties the top of one to the bottom of the other, like the parallel edge on an old style drafting table.
Hydraulicly, by using interconnected valves that equalize the pressure.
Mechanically, by using external guides that keep the driven piece straight and thus equalize the loadings (e.g. guide rails and shoes).
-- John Brannon (email@example.com), March 17, 2004.
Thank you John. Mechanical solutione are quite an headache now as the elevator is operating. Could you explain more about interconnected valves? Do you mean a connection between two rupture valves? How can this effects unbalanced loads on rams? If it's not too mach to ask maybe you can email a sketch to me. Thank you David
-- David Touito (firstname.lastname@example.org), March 18, 2004.
very hard to do and not have some sort of problem....Otis has Problems....we have major probs with certain Thyseencrap....even Schindler/deve have probs....with 2 rams doesnt really matter how they are equalised one still seems to get out of synch ...might take months but customer gets the shits because the same problem keeps reoccuring...just have to resynchronise every maintainance visit.
-- dayle (email@example.com), March 18, 2004.
David, the valves are flow control type, designed to equalize pressure in branches. I seem to recall that the leading supplier is BARKSDALE:
The former Rotary Lift/DOVER made thousands of succesful systems using multiple jacks. A couple of outstanding ones are the 75,000# freight elevator for the NY Coliseum and the multiple section stage lifts for the Metropolitan Opera in Lincoln Center.
-- John Brannon (firstname.lastname@example.org), March 18, 2004.
If you know what you are doing, you can wire a timer to lower on to the buffers at a certain time and period with full use of safety circuits, to resynch the jacks.
-- mike (email@example.com), March 26, 2004.
Mike, I believe your answer applies to multi-section (i.e., telescoping) jacks. The question , I think, was about multiple jacks, i.e., more than one jack for a single platform.
-- John Brannon (firstname.lastname@example.org), March 28, 2004.
I solved a similar problem using the timer to land the car on the buffers.....instead of parking the car on a floor..the pistons pretty much stayed in synch after that good luck
-- Glenn Davis (ElectricElevator@aol.com), May 07, 2004.