Working on a Champion C70A (serial number 26 412). I am not very familiar with these small graders and cannot seem to find any service or testing information anywhere. The machine worked fine on its last outing but after sitting for a month or two the contractor tried to move it from the lay down yard and could not get it to move. I fiddled with it a bit and it started to work, but seemed a little sluggish in both drive and hydraulic functions. Gauged the hydraulic circuit and found 2000 psi on the blade hoist against relief. (And that seems about right given the very small pump that it has). But the drive seems very wonky. It will reverse with normal power at idle but will only go forward a couple of feet before it locks up and loads up. At high idle it locks up in both directions. The oil (hydraulic, common system) looks to be a bit water contaminated. I am having a hard time deciding whether or not that is a clue. None of the hydraulic samples I have taken actually separate out. It might be possible that the oil is aerated. But I found (clear) water in the screen below the hydraulic filler cap so I think it is just very minor water contamination that has gotten past the seal on the filler neck. The system is air cooled so there is nowhere else for it to come from. I have bypassed the park brake valve with very little change in performance. I have gauged the park brake circuit. Seems to be a pretty steady 200 to 220 psi. (Which again seems reasonable to me.) I am sort of out of ideas at this point because of a lack of actual data to judge anything by. There is very little tech info out there on these mini graders. So I am hoping someone here has a service manual, some advice or even perhaps that motorgrader is still haunting this forum.
I know nothing about Champion machines, but 200 psi charge pressure is very low for a hydrostat system, and if it has spring brakes they usually come on around that range, though YMMV.
You may be right. I am kind of grasping at straws here. I am down to researching the two components that I actually have data plates on. The sunstrand pump and the Mico park brake. I seem to remember that the standby pressure of the pump and the brake release were in that neighborhood. Though I will freely admit that this sort of research is usually done when I get home and almost always involves a glass of bourbon.
The guy that built and sold the compact Champions was on here, can't remember his handle. Abernathy was his last name. Not sure if he is still active
I have a customer with a Champion 70. It’s a pretty base hydrostatic system. Have you checked the main relief pressure?
I think his handle was motorgrader. I would like to hear from him. I have not checked the relief because I don't know where to or even what pressures I would be looking for. I am guessing somewhere around 3200 psi. But was hoping for more info before I try.
Got a model number or picture of the drive pump? The 20 series needed about minimum 160 plus case pressure so maybe you're in the ballpark. If the motor(s) have flushing blocks, they'll drop the charge pressure some when you pressurize the drive loop to make the machine move.
22 series sunstrand. 22-2880jb-rbdx. Only one drive motor with the park brake assembly between it and the differential. I don't know if you are calling something other than I do but I am not sure what a flushing box is. I thought that was a service tool for cleaning hydraulic systems.
If it's a sundstrand motor as well, there will be a manifold block bolted to it with two high pressure relief valves and a. Charge relief with shuttle valve. Did you check the charge pressure while trying to move it? Flushing valve also referred to as Hot oil shuttle
Not yet. I needed to get #16 code 61 adapters to plumb it into my flow meter. Got those this morning.
Finally circled back to this machine yesterday. Wow, four months later. This grader is very rarely used so it got seriously back burnered. I was a little suspicious that the ball valve on the suction side of the hydraulic tank wasn't actually moving with the lever. There wasn't very much resistance on the handle. So I pulled apart the plumbing and then tried to open the valve and almost nothing came out. Poked a finger up the hole and found the valve was actually open. So, duh. Water contaminated oil= gummed up suction screen in the tank. Cleaned the screen, cleaned the tank, refilled with new oil and blew as much of the contaminated oil out as I could through the tank return filter housing. Fired it up and when the air worked its way out of the hydrostatic pump and motor everything was back to perfect. Some days I really impress myself. Days like this I wonder if I should get a blue vest and become a greeter at Wal-Mart. Big thanks to those of you that tried to help me with this one. Time for that bourbon.