Originally Posted by sganesh

Dear experts,

What is the meaning of term "Break-In" when the belts are changed ? How is it related with the belts off-tracking? How long usually does it take?

Are the belt off tracking characters common for both steel cord & fabric belts?

Thanks a lot & Regards to all,

New steel cord belts track well from start-up. There may be a 10-20 mm change over a month of loaded operation from first measurement. The steel cord wire strands take an internal hertzian set, after taking pulley bends and design tension loading.

Fabric belt will not track as well as steel cord construction as a rule. It needs ironing, depending on the fabric, its weave configuration, nylon vs. polyester (nylon stretches and cold flows more than polyester material),it also absorbs water, and there are many other attributes that affect fabric belt permanent stretch such as harsh versus soft-starting or braking, gravity and fixed take-ups, ..... A fabric belt can take several months of design loading to stop counterweight creep. Sometimes fabric creep never stops, depending on the severity of starting and stopping. We have seen fabric belt width shrink inches from abusive operators. No easy rule to apply. Know the material, the design and the operator. ■

Sorry,

Fabric tracking, during break-in, will vary with width, construction, material, and installation errors. Since it is many times more compliant with a lower elastic modulus that varies with time, it will tend to wander more. Wide belts wander more than narrow, I assume, from the added strands that can deviate, their strand errors sum to the overall tracking anomaly. Much harder to pick a number. Maybe this is where the 6% CEMA, DIN and ISO standards edge clearance allowance came from, before you try to control lump spillage. The 6% does include construction errors. It is a fairly old standard.

I have measured many steel cord with tracking anomalies. A well constructed steel cord belt will not wander beyond 25 mm from side to side over its length, except at splices and at factory press breaks. We set the tracking error standard, in our belt construction specification, a manufacturer must meet that forms a part of their quality control warranty. The same cannot be said for fabric. You must know the manufacturing procedure, the reeling procedure, stamping of construction direction, and finally the installation procedure, that they all follow the same rule, orienting the leading and trailing ends in the identical manner. You must watch for installers that have multiple installation locations that they will adhere to this rule. If not, two belt sections can mistrack more than 150 mm between reels. ■