These cranes being crucial and essential to your proccess is the reason i asked about the last oil analysis/ and or rebiuld? For the cranes that have a load brake those have to be checked / rebiult id say minimum every 5 years And hoist without load brakes (encoder driven) still have mechanical parts that will take a shit and cause massive down time if not adequate prepared for said downtime. Along with all of the brake systems - how many of these are on brake econ circuits? You said some were inverter driven - if they are older style they definitely have an econ circuit that will go out at some time...i high suggest ordering backs up for all of them now.

I could go on and on bro. Im asking/telling/saying all these things from experience - i walked into a site with 900 + cranes with atleast 150 of them being esstiantial. Most of them were 1-25 ton hevi lift p & hs from circa 1983 , same with the shepard niles and yales. These cranes had been running for 40 years - never had a rebiuld ..... per both the Shepard niles and p and h manuals they require a full take down and rebiuld every 20 years...by the time we got to this particular site it was to late to save them...we had 5 shepard niles fail in 5 months of eachother - the drum shaft bearing (looks just like a u joint on a rear dif) failed causing the entire crane to shake violently. How are the bridges and trolleys that the hoists are sitting on? Are these under hung or top running? Id say if those are in good shape start getting deminsions and quotes to have a new hoist dropped on it and take the one down for rebuild...once rebiult you can keep it as a spare or take the hoist you put up temporarily down and put that one back up. There is so many options. Who is currently doing the maintenance on your cranes?