Hello all 1st post looking for assistance. We have a JLG 45HA. It was working fine but had a hydraulic leak due to cracked vickers block. Pic attached. We replaced the block, but after getting it back together the tower boom would not go down. Our mechanic was able to get the tower boom down (I think he reversed the up and down lines). After lowering the tower boom (and reconnecting the lines properly) it would work up and down except each time we raised the boom it would go down and stop slightly more extended than the previous time. After several extension and retraction cycles the tower boom gets stuck fully extended. Can anyone provide any guidance as to what may be causing this? Are there any guys on here who service these near Elizabethton TN (Northeast corner of TN near Johnson City TN) who perform the work on site? Thanks in advance for any assistance. Steve in TN.
Welcome to HEF FORANE. :drinkup Whatever is causing your problem, it's not that accessory valve that you have in pic above. The accessory valve has three cartridges in it as follows (left to right in pic); 1) sequence valve, controls system standby pressure at 350 psi, 2) pressure reducing valve, provides pilot pressure to Vickers proportional control valve at 450 psi, 3) main relief valve, set at appx 3200 psi. Without knowing more details, your problem may be in the various limit switches/valves that control the tower boom. These components prevent the tower boom from lowering until the tower boom extension sections are fully retracted. If you do have the extension fully retracted, you may have a faulty switch or valve causing the tower to not come down.
All other booms fully retract. Thanks for your post.