The following 4 components determine the top of car clearances:ġ. Overhead beams and construction not located over the crosshead clearance (2.4.10) The top of car clearance areas that need to be addressed are:ģ. I'll mention a few unusual situations as we progress - for now we just need the basics. We will be examining a "common" elevator installation - an overhead traction machine in a standard machine room, 1:1 roping, standard pit and overhead construction - nothing unusual to speak of. (The 2000 edition and the 2005 supplement to the 2004 edition have the same requirements.) We will be using A17.1-2004 as our reference code. Now that we have an understanding of this significant safety feature we can begin to analyze the clearance requirements found in Section 2.4. This should not become a problem if the equipment is properly maintained. (Bethlehem Wire Rope))Īn Improperly Maintained Traction Elevator With
(Left image "borrowed" from Wirerope Works, Inc. I have not observed this phenomenon myself but I have heard from reliable sources that it can occur.Ĭross Section Of A Severely Worn Sheave AndĪ Corrugated Sheave Produced By "Rope Imprinting" If the drive sheave is damaged (the grooves are deformed, severely worn, and/or "rope imprinting" has occurred on the sheave surface) and there is a significant amount of rope on the counterweight side (which equates to a significant amount of weight) enough traction may be available to pull the car into the overhead. There is at least one flaw to this safety feature.
This applies to the car landing on it's buffer(s) as well - the counterweight stops moving in the up direction and if provided with enough clearance it will also be free from damage. A person and/or the equipment on top of the car will not be injured or damaged if the correct amount of clearance is provided.Ī Properly Maintained Traction Elevator With Adequate Top Of Car Clearances There is insufficient traction to pull the car up into the overhead - the ropes (belts) "break" traction. The code sections for determining electric elevator top of car clearances can be a bit overwhelming at first encounter - but I am going to explain the procedure in a clear and logical way.at least that's the plan! As you may know, one of the key safety features of a traction elevator is that once the counterweight has landed on it's buffer(s) and it's weight is removed from one end of the suspension means the car will stop moving in the up direction - even if the drive fails to turn off.
(Update #20 Top of Car Clearances - Hydraulic Elevators (3.4.4).will be found here.) Update #19 Top of Car Clearances - Counterweighted Elevators (2.4.6)
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