Hello everyone, I’m a mobile automotive mechanic working in the DFW area. I was called out to a sky track that is grinding when going forward or reverse. The workers on scene found the hydraulic oil very low and filled it up. Once I was on scene and heard the noise for myself it sounds like the brakes are dragging when trying to move forward or reverse. There is no hydraulic movement from the boom, the steering, or the feet. When you first try to touch the steering wheel it acts like it’s going to move but only moves a few centimeters. You can kind of see the feet move when you push the button to lower it if you rev the engine and lower at the same time. There is absolutely no boom movement. I have already checked the coupler on the hydraulic pump, the filters are good and not clogged. There is fluid inside of the pressure hose. Fluid is getting to the pump. It doesn’t whine or make any typical noises. My guess is the main hydraulic pump is out. I’m trying to associate why it feels like the brakes are engaged, does the brake system work like a tractor trailer? Does it need to have hydraulic pressure in order to release the parking brakes? I just need a little help with the operation theory and how it all works. My guess is the hydraulic pump is out that’s why I have no hydraulic movement and the brakes will not release. I’m just hung up on the part about the brakes releasing. I would hate to be overlooking something simple like a safety switch. From what I can tell though all of the safety switches are functioning correctly. When you disengage the main parking break you can feel the hydraulics click like they’ve been engaged. When you put it in Ford or reverse the transmission jumps in the selected direction but the vehicle stay still. I can see all of the shuttles moving on the outside of the control block. It even feels like maybe there’s fluid going through the lines, but very difficult to tell if that’s not vibration from the motor. Any help would be appreciated, how far off am I? Lol
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