Have a GP30 S/N 7AN10318 which we are looking at for a new customer.
Problem started with the reciept of a call advising that the brakes were locking on when the truck got hot. Our engineer (25+ years service) drove truck and felt brake pedal was particuarly poor, so bled the brakes getting out a fair bit of air. Happy with removing the sponginess of the pedal, he drove the truck around to get nice and hot and was happy that it had solved the problem and the brakes were no longer binding.

Just over a month later (but only 20 operating hours) same call for brakes locking on. Same engineer found the master cylinder push rod was overadjusted slightly with no free play in the push rod. Simple to sort by a quick re-adjustment getting the required free play and thought that would be the end of it.

Three months later & 80 hours operating, another call, but this time brake pedal dropped to floor and brakes inefficient. Same engineer used, can't find anything wrong brakes, pedal good & solid, no fluid leaks, linkages all good, drums ok, shoes ok, wheel cylinders ok. The brakes work, and are "good", but compared to sister machine (same model and age) on site, they are definitely less efficient. The engineer says if anything the brakes on the other machine are too sharp and almost put you through the mast when applied, but customer seems to like it that way. However the customer says both trucks used to be "sharp" before getting any of the work done.

Work? what work ?
Turns out we have inherited a problem another forklift company couldn't fix....ok what work have they done ? wea re advised that they have replaced just about everything. We advise that if there is likely to be anything wrong with the system (the exceptionally simple system with no fluid leaks) it's (pound to a pinch of salt) got to be master cylinder (which has alreday been replaced by the other company). So we replace master cylinder again and have good fun trying to bleed the brakes thereafter, and check the whole system over and are happy that everything else is working ok and is adjusted accordingly, including the inching system on transmission, brake shoes then handbrake etc. Everything seems ok, customer happier that brakes a bit more efficient (but still not as good as other truck).

One month later a new call....customer says puddle of fluid on floor under truck and brake pedal dropped to the floor. Same engineer attends. The puddle on floor is water (or at least not brake fluid and certainly not from this forklift truck) and no fault found with brakes. Engineer strips out drums, checks wheel cylinders and mater cylinder again, no leaks wetness or seepage, and fluid level in resevior spot on. Customer says brakes are still inefficient compared with other truck. Engineer suggests to fit genuine Cat shoes / drums and wheel cylinders to see if makes a difference.

So, does anyone have any suggestions or knows of any common issues with these trucks / braking systems or has anyone come across this before, prior to us offering the option to the customer ? will look a bit silly if we fit new shoes, drums and wheel cylinders and it makes no difference......

TIA for any help.