Acceptance Test After a Traction Modernization
You are witnessing the acceptance test of a modernized 4-stop traction elevator: rated speed 1.0 m/s, rated load 1000 kg, new gearless machine and controller, existing car safety gear and guide rails. The governor is new. With rated load, the governor trips at 1.05 m/s. The safety-gear test is then performed: the car slows, but the safety gear does not grip evenly, and the car comes to rest only after the machine brake applies. The contractor says the guide rails are oily and wants to clean them and repeat the test. The building owner wants occupancy on Monday. The alteration permit is on site, but the TSSA inspection has not been completed.
1. The governor trips at 1.05 m/s on a 1.0 m/s elevator. Do you accept it? Explain.
Read the worked answer
No. For a car safety governor, the tripping speed must be not less than 115% and not more than 140% of rated speed. At 1.0 m/s rated speed, 1.05 m/s is only 105%, below the minimum. A governor set that low can trip during normal operation or during a normal leveling overspeed, apply the safety gear when it should not, and create a sudden stop with passengers aboard. The correct action is to adjust or replace the governor spring or setting to bring the trip speed into the required range, reseal the governor, and repeat the test. The result must be recorded and witnessed. I would not accept the governor as tested, even if the car otherwise runs smoothly. This is a safety function, not an adjustment to be deferred.
2. The safety gear did not stop the car; the contractor wants to clean oily rails and retest. What is your position?
Read the worked answer
Cleaning the rails may be necessary, but it is not sufficient as a conclusion. A safety gear that fails to grip evenly can result from oil or grease on the rails, incorrect safety-gear adjustment, worn gibs or rollers, misaligned guide rails, a binding linkage, or unequal pull on the safety blocks. I would require the contractor to inspect the guide rails, safety-gear assembly, linkage, and clearances before the retest. The retest must be performed under the code conditions with rated load and witnessed. If the gear still fails to stop the car or marks the rails unevenly, the car must remain out of service. I would not accept a “clean and try again” approach without identifying the cause. The owner’s Monday occupancy date does not override a failed safety test.
3. What must be completed before the elevator can be placed in service?
Read the worked answer
The governor must be adjusted and retested within the required trip-speed range. The safety gear must be corrected and successfully retested with rated load, with the rails and gear inspected and the results recorded. The TSSA inspection of the alteration must be completed and any deficiencies cleared. The contractor must provide the acceptance-test records, governor certification, safety-gear test data, and a statement that the car is ready for service. I would also confirm that the door interlocks, terminal limits, buffers, and emergency operation have been tested as part of the modernization. Only then would I recommend release to the owner. If any test fails or the TSSA inspection is incomplete, the car stays out of service regardless of the occupancy date.