single speed elevatorsgreenspun.com : LUSENET : Elevator Problem Discussion : One Thread
has anyone analysed the factors effecting leveling accuracy of 1 speed traction elevators. my problem is that the levelling varies upto +/- 3" between full and no load. Further tightening of the brake produces excessive stopping jerk. backlash/end play is minimal(~0.002"0).Any ideas will be appreciated.
-- rushad divecha (firstname.lastname@example.org), July 23, 2002
The fundamental determinator of landing accuracy is approach speed, i.e., the velocity of car movement just prior to the final stop. For satisfactory results, this speed should not exceed 25 feet per minute.
Since with single speed AC the full speed is also the approach speed, the accuracy is inherently limited unless the full speed is 25 fpm or less. Usually, such a low speed is not acceptable.
Depending on speed, the operation you are experiencing may be normal.For typical speeds used with SSAC (75-100 fpm) you should be able to do better than what you indicate.
-- John Brannon (email@example.com), July 23, 2002.
i would be happy with a +/- 3mm floor level with full and no load. by tightening the brake to get it even more accurate u will only get a call in a month or 2 with reports of it not stopping level...eventually u wont b able to tighten the brake ne more and u will have to replace the shoes...so my suggestion is to leave it as is.
-- john (firstname.lastname@example.org), July 24, 2002.
Hopefully you have not touched the selector......If the selector is properly set it's possible to adjust the brake for about 3" of slide.allowing the car to be level with out load,and reasonable with heavy load....this of course will depend on the condition of the brake shoes....If you have ahhhh adjusted the selector..."GOOD LUCK" The entire system may have to be adjusted in from scratch....
-- Glenn D (BONER3988 @aol.com), July 24, 2002.
Good luck. A single speed a.c.motor operated machine is directly affected by the temperature and the load it is carrying. Your problem is more than likely brake associated. Tightening the brake is considered a bandaide approach. It would be in your best interest to have the brake re-lined. Then you will see most of your stops be more consistant. Let ne know how it comes out.Ed
-- Ed Markham (email@example.com), July 29, 2002.
Tightening up the brake will get you over the usual wear prblems for a while. As the wear increases you may need to look at other aspects of adjustment, airgap is important and lift also will play a role in drum contact. If I start every month banging up the spring tension then what I ususlly do is strip the solinoid down and clean all the debris out reassemble and set up from scratch taking into account the above airgap etc. Single speed jobs need that "snap" down of the shoes on the drum to kill initial velocity and the slide smooths out the jerky stop. Good luck
-- Steve (firstname.lastname@example.org), September 03, 2002.
Have you adusted the amount of brake shoe lift, ie: the air-gap, this should be absolute minimum without the shoes rubbing the drum, this will reduce the volocity the brake shoe when approching the drum and thus reduce the amount of jerk felt
-- bj (email@example.com), September 09, 2002.