When I was a helper I worked with an adjuster who would start at 40% and add weight till he got the current in the up to match or be close to the current in the down. All his cars always ran nice

Overbalance is dictated by the machine. Ie: a geared Hollister machine is 40%, imperial gearless 50%, etc. If this is for a mod you are allowed up to 5% change in car weight. I have seen Companies do this and not rebalance the cars. I don't really agree with this, never seen a modded car that you didn't have to add weight to. the cars in question were old Otis cars from the late 40s that had the complete car cabs replaced, yet still the original data tags. When I did cat 5 testing I checked balanced load @ halfway and lifted the brake and the car took off. The current was also not "matched" like bowtie mentioned. I think overbalance was suppose to be 4o% and it was closer to 48%, about 200# need to be added

Correction to what I said; the car would have the balance load in it and he'd run it up and down watching the current and add fillers to the cwt stack as needed to get the current close

Thanks for your input gents. I wasn't sure if it played into the overall traction calc or anything like that. I have seen on mods where some old dover geared units were at 28% overbalanced and had to add 500 lbs. the cat testing finds a bunch of overlooked things like tayto mentioned.

The main thing I don’t see many people check is the rated sheave shaft load. What’s the total system weight on the machine, car, cwt, roping, monomass.

thats a good point Hex67 - something to check for sure especially on alterations.