Home Forums General Discussion Technical Questions buffer switches

Under what circumstance are buffer switches required by code?

I can only find them listed as needed with type C safeties, and gas return oil buffers. I am not clear if oil buffer means, gravity return oil buffer, spring return oil buffer, or if it even matters, and under with scenario are they actually required beyond the two references I found in the code.

Depends on the code the cars fall under and the AHJ. Older cars could run with open buffer switches as long as they were within buffer striking/low speeds. Newer code calls it as a safety device so it has to stop the car. Under 200 fpm in most cases don't need a switch.

asme a17/csa b44 latest edition I have on hand is 2007. Yes a buffer switch is a safety device, but there is no mention of speed having anything to do with the requirement for a buffer switch that I can find. Do you have a code reference?

I think all taction buffers besides spring, should have buffer switches. When I'm in the machine room, I want to know if I'm on the car or cwt buffer.

2.22.3.1 shows spring buffers up to 200fpm. 2.22.4.5(c) shows gas spring-return oil buffers have switches. gravity-return buffers don't require. The speed of the car, along with other considerations are what say the type of buffers needed. This is the latest A17.1, but I believe this is how it has been for a long time.

Never seen a buffer with safety switches attached, even on 7m a second lifts. Guess it wasn't required in our regs. Also you would still know the lift has over travelled when it has gone thru the over travel switches.

Yes I take back the type c reference, couldn't find that in the code, so I must have made it up

Thanks for the follow up, basically confirms what I found in the code book, if I ask around at work I hear different ideas, but there is only one code to follow.

Yes you would know. What I use buffer switches for is to make sure the buffers return within 90 seconds. I run the weights and/or car up off the buffer and snatch my jumper off and watch and count for the switch to make.

A17.1 2009 sec 2.22.4.5(c). Switches required for gas-spring return oil buffers. Regular spring oil return buffers do not require switches.

Yeah sure. All we did was use the car on maintenance on top of the car to test the buffers and see if they returned to normal state.

Buffer switches are used to determine if the Buffer has returned to within 1/2 in of full extension on all cars with Gas Spring-Return Oil Buffers. They must return to full extension within 90 seconds. The Exception is Type C Buffers. Here the Auxiliary Safety Plank has Switches to prevent movement if the Plank is out of level by more than a 1/2 inch, and another Switch to prevent movement if the Buffer is compressed more than 10% of it's stroke. Also another switch if the Oil Level is below minimum. All good reasons that there are only a few Type C Buffers around. I have only seen Type C's on Montgomery Elevators.