Hi,New member here, with a log loader problem.

badgascoupe · May 28, 2015

Hi,Well found this sight while looking to solve a hyd problem with a log loader. I have a Prentice extendaboom loader,originally a sheetrock loader.Put the loader on a 3 axle Mack. I took off the rock forks and added a grapple. Here's the problem,all the loader functions operate off their seperate spools on the valve body,however the grapple dosen't have enough pressure to hold the log.I had the grapple cyls repacked still same issue.Any ideas? Thanks,Sean

J_J · May 28, 2015

What kind of pressure do you see on the grapple.

If you resealed the cyl, then you may need to replace the valve. If it is a stacked/sectional valve, you can replace each section.

Switch spools and check the pressure.

Leejohn · May 28, 2015

Check the grapple spool and see if it has it's own reliel valve. All the spools could have there own relief valve.

oldnslo · May 28, 2015

Does the grapple leak open under load or will it not close with enough force to lift the logs?

If it leaks open under load then you could have a leaking spool. Installing a load holding device like a P.O. check or counterbalance could solve this problem.

If not enough force you will need check system pressure if it is as rated specs for your machine you will need do one of the following:
increase the cylinder sizes
chnage mechanical linkage so that is provides more clamping force

badgascoupe · May 28, 2015

Hi JJ,it has a greshen 6 spool stacked valve.I have moved the grapple lines to different spools on the body as it would creep closed in its regular valve location.At other spools on the valvebody it opens and closes correctly and dosen't creep closed.I replaced 2 power side fittings coming out of the pump to the valve body with ones that have a port to add a pressure gauge to them,Graingers had to wait a day to get the gauge for me.

badgascoupe · May 28, 2015

Hi Oldnslo,The grapple valve creeps closed when you let go of the handle.I moved it to other spools and it works correctly( stays where you stop it) other then not enough pressure to hold logs.Plumbed in elbows with ports to add pressure gauges to it,waiting on Grainger for the gauges.