Just changed some Otis belts on a 2000Kg Gen2, all went well. returned to service and tested to all floors was just about to leave and filling out log card when we noticed the lift had moved slightly.
On looking further we found that the belts are creeping over the sheave and the lift is slowly moving up, seems a lot when you look at the video but in relation to car its about 10mm every 15mins.
Checked tensions and all springs are within 1mm, belts are original manufacturer, no changes have been made to affect the balance, there is no coating on the belts that requires removing or cleaning and its purely slip no drum/sheave movement.
Any ideas appreciated, posted a video here
Managed to get hold of an official Otis belt cleaning kit so we will see how that goes tomorrow, if not next would be a half load balance test i suppose check it was balanced on installation although there was never an issue before with the old belts.
Worse thing is belts were fine until an insurance man buffered the CWT, not sure how he managed to do it as we couldn't replicate it but it appears the lift car top shoe impacted one of the belt monitor clamps and damaged the monitor and put a small rip in one of the belts....
I think the main culprit was the sheave/drum pulled belt aside and gave it a good scrub.
Regular wire ropes don't have this problem...