Long time lurker, first time poster hoping to get some guidance. I'm dealing with some brake issues on a Skyjack SJ7027. The brakes will intermittently stick on restricting forward and reverse movement. I checked the solenoids for the brake valve and dump valve. The solenoids are getting power and are working (I did swap out the solenoids to confirm). I removed the brake valve and powered up the solenoid and can see the spool moving in the valve. When I power up the dump valve I can hear and feel the valve moving but the end of the spool does not move. If I push on it I can feel spring pressure but it seems the coil will not hold it in. I was also told that when operating the lift function it will not lift when there is extra weight on the platform (still under the load limit but above the weight of two people).
Based on what I'm seeing in the hydraulic schematic, if I'm reading it right, the brake dump valve could potentially affect both circuits. I'm thinking that the dump valve is not closing off the port to tank properly and this allow oil to leak out of the brake circuit preventing the full release of the brakes and potentially could allow oil from the lift circuit to leak to tank limiting while using the lift circuit.
I did notice that the troubleshooting guide indicates that a faulty brake feed valve will prevent the lift "up" function but this lift will go up just not if there is a few hundred pounds of extra weight.
Can someone tell me if I'm on the right path or correct me if I'm wrong?
Thanks very much for your help
Emetech
Based on what I'm seeing in the hydraulic schematic, if I'm reading it right, the brake dump valve could potentially affect both circuits. I'm thinking that the dump valve is not closing off the port to tank properly and this allow oil to leak out of the brake circuit preventing the full release of the brakes and potentially could allow oil from the lift circuit to leak to tank limiting while using the lift circuit.
I did notice that the troubleshooting guide indicates that a faulty brake feed valve will prevent the lift "up" function but this lift will go up just not if there is a few hundred pounds of extra weight.
Can someone tell me if I'm on the right path or correct me if I'm wrong?
Thanks very much for your help
Emetech