we have a jlg 40ha. We blew a hose on the lower tower boom cylinder and had to replace it. After replacing it we found that the tower boom cylinder will only extend but not retract. We also found that the uprite cylinder will not move at all. We played with it until the lower boom cylinder is now fully extended and will not retract. When the hose ruptured the lift dropped and stopped. Can anyone tell me where to look to reset the cylinders? The hoses jump when you toggle the ground switches. Can’t find any way to lower the cylinder. We tried the red knob under the controls but that didn’t do anything. Please help!! Thank you!!!
I’m starting to think I might have a bad pilot operated sequence valve but I’m not 100% positive
So it was working fine before your hose blew out correct ? Who made the hose ? I’d take it off and check the crimp. Maybe they over crimped the hose crushed the inside of the fitting. Also some less experienced hose guys cut the hose and never blow out the inside. They make the hose with all the junk inside from The cut. Had a 19’ scissor lift that I put a hose on and a piece of rubber from the hose cut went right into the valve and stuck right there. Worth checking since it worked before the leak and hose replacement
Did you try the procedure on the sticker by the red knob in the pic of the ground controls that you posted? Usually when articulAting jlg booms wont lower all the way that fixes it.
Emergency lowering valve will only allow the primary lift cylinder to lower your still having an issue with the extended retract circuit correct ? There is no cylinder reset. Your main lift cylinder has two holding valves. On in each side right above the pin. The sequence valve senses the difference between the load and the pump pressure. But to the original question was the machine working correctly before the hose failed and was replaced ?