hello, I have a customer with a Volvo 210b, the hydraulic pumps gave up in it so we fitted recon service exchange pumps, also a main relief valve and I went through and set every pressure on machine to spec main relief servo all port reliefs. Machine was working fine when I left they called today said the hydraulic oil was overheating tank was too hot to touch. I went to it this evening cleaned the cooler and removed and inspected check valve going into cooler I backed off regulators on pumps a bit as it seemed to be pulling engine down a bit. The regs came off his original pumps. I drove it for an hour and checked temps every so often. Temp at the tank was hitting between 50 and 60 degrees celcius, about 10 degrees of a difference across the cooler, what I did notice is the slew motor is not right it must be bypassing internally it runs on a lot after you stop slewing. Temp on top of slew motor was 70 degrees at one stage. I also had 70 at the pumps but I would imagine the pumps should be the hottest part of the system? What should be the hottest hyd oil should get and do you guys think the bypassing slew motor is enough to cause this? I told him slew motor will have to be sorted and go from there
Please see attachments. Let's verify slew is continuing too long.
Once you've established whether or not the swing is going beyond spec, then we can look at anti-cav's and brake apply etc. For now, have you confirmed that oil is traveling through the cooler. The thermostats were known to come apart and either block oil flow to cooler or let it flow unrestricted. Usually a blockage occurred. If it didn't overheat before, odds are, something is wrong in set-up. Not knocking your work, just stating **** happens. Please explain your procedure for establishing pressure and adjusting the main.
Swing is travelling way too far i know by just driving it. To set the pressures i fitted the new main relief that is to be set at 323 bar without the boost. The port reliefs are higher on boom and arm functions cant rember the spec but i think it was 350-360 ish. So i turned up main relief over the spec and set them port reliefs then when they were all set right i readjusted main relief back to spec. I had the thermostat for cooler out and it is in tact. It had been heating the oil before pumps were replaced but i was putting it down to the worn pump bypassing.
Is the tank maintaining positive pressure. Did you service the sump strainer and the 3 hydro filters ? Did you find anything in the case drain. Do you have the ability to measure control pressure at the pumps? I'm kinda wondering if you got a false signal causing the pumps to stay stroked
Changed all filters and checked strainer. Checked control pressure to both pumps its fine. Pumps are backing off there is only a couple of bar pressure at idle with no function activated. Also checked to make sure hammer circuit wasnt constantly activated. And yes pressure on tank when i press vent on top to release air
Found nothing in case drain old pump didnt break up it was just worn where swash plate pivots and some pistons had play in them
I show track relief at 392 bar. So, I would pin the tracks and crank the main to hit the travel relief. Then reset all your port reliefs. Then pull your main down to 324bar +/- 14.5 bar. You wanna see 343 bar +/- 14.5 bar on boost. You've already verified the option is not causing you issue. Then verify you have 39 bar to each pump at port Pi1 &Pi2
see attached parts doc. Can you T in a gauge at hose 31 & 30 at pump. You want to see full pilot oil of 39 bar and it should fall off towards 0 as you place the demand on the pump. Would also like to know what the standby pressure is of each pump at full throttle with no demands placed on it. It's gotta be pretty significant to generate high heat. You should also hear quite a bit of hissing somewhere particularly at idle.
Yes i have checked these 2 lines they have full servo pressure when no service is touched and they fall off proportionally as you move a lever as they should. Standby pressure is low maybe something like 10 bar at idle on both pumps. Does anybody know what flow i should be seing from the case drain of these pumps. I am a little iffy about the reman pump.
With no load on the pumps, it should barely be a trickle. Rule of thumb, never exceed 10%rated flow of pump through case drain. If you run full throttle and pin your track to prevent travel, you should be able to remove line to case filter from pumps and measure into a bucket.
Do you mean 10% when the machine is revved up and working under load?
Yes.