Okay just did some testing mine has the block deals on top of the pumps my main pump seems to be just on all the time type deal tested it out and I get a relief pressure around 2400 psi at 1800 plus engine rpm. Now the second pump which has a line the goes to the steering gear box and then another line goes and tees into the main pumps discharge line I am assuming it is the 2nd stage for the main hydraulics. At low rpm up until about 1500 rpm it will make pressure without moving the controls at 1500rpm roughly it will dump to no pressure. Now... If you roll the bucket back to the stops at low idle then hammer it we see no dump off of pressure it goes right on up to 2400 psi so both pumps feeding the main system show the same pressure above 1500 rpm but help we 1500 rpm the main 1st stage pump will not make any pressure unless you activate a lever. But the 2nd stage will. I'm going to get a video to clear this up a little and post a link
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New to me Michigan loader
- Thread starter Randy v.b.
- Start date
oldseabee
Senior Member
The steering pump is a totaly different animal, it monitors flow and not pressure, low idle up to 1200 RPM has both sections providing full flow for steering at low RPM, 1200 to 1600 RPM the flow out of the rear pump section is gradually reduced and that flow is dumped back into the supply line to the main hydraulic valve assembly, at 1600 and above all the flow from the rear pump section is all diverted back to the supply line to the main hydraulic valve. To simplify all that, 1. At high RPM low pressure one section of the steering pump diverts to the main valve. 2. Both sections of the hydraulic pump and one section of the steer pump supply the main valve. 3. Low RPM low pressure, both sections of the steer pump supply the steer valve, both sections of the hydraulic pump supply the main valve. 4. High RPM high pressure, one section of steer pump supplies the main valve, one section of the hydraulic pump dumps back to the inlet side, so one section of the hydraulic pump and one section of the steer pump supply the main valve and the other section of the steer pump supplies the steer valve. 5. Low RPM high pressure both sections of the steer pump supply the steer valve, one section of the hydraulic pump supplies the main valve the other section dumps back to the inlet side.
oldseabee
Senior Member
That test port on the valve on top of the hydraulic pump pressure should drop when the pump drops one section at about 1800 PSI.
oldseabee
Senior Member
That test port on the valve on top of the hydraulic pump pressure should drop when the pump drops one section at about 1800 PSI.
Also some early machines were set up just to send the diverted oil either to the return to tank or back to the inlet of the pump. My last post was the way the system works when the pumps were plumbed to divert the dump oil from the steer pump to the main valve instead of dumping to tank return.
Also some early machines were set up just to send the diverted oil either to the return to tank or back to the inlet of the pump. My last post was the way the system works when the pumps were plumbed to divert the dump oil from the steer pump to the main valve instead of dumping to tank return.
oldseabee
Senior Member
I should have added that you had to be above 1200 RPM for the main pump to dump one section
so assuming you watched my video the test port I pointed out(the very first one I pointed out) that one should at 1200 plus rpm and at 1800 psi it should drop down to minimal pressure? if that is correct then It is not dropping down it goes right up to 2400 psi at all rpm ranges.
oldseabee
Senior Member
Sounds like that's where your engine bogging down and hydraulics slamming is, the valve on top of the pump. Now you have to decide if you want to take it apart and have a look or buy a new one, like I said earlier stuck spool was a bit of a problem on those early pumps but you also have a pressure relief valve in there that dumps pressure that has built up in the spring area behind the control spool so the pressure on the other end of the spool can now shift against the spring and dump the front section of the pump. could also be trash in the high pressure poppet of the relief valve, one thing to try would be to back the adjustment screw off, be sure to count the turns so you can put it back in the right place then run the machine at high idle for a few seconds to blow the trash out of the high pressure poppet then reset it and see if the valve is dumping like it should. I like to do easy Sxxxt first then look inside to try to fix it but that would be me a little lazy and cheap.
By the way FYI I was born and raised in Colorado, graduated Lakewood High School 1956.
By the way FYI I was born and raised in Colorado, graduated Lakewood High School 1956.
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oldseabee
Senior Member
Did some more digging and found that only a very few B models were set up to divert steering pump oil to the main valve, mostly as a test. The C models were produced with the diverter system and some pump changes. the pumps you have work the way I said, the main thing was that they dumped the oil back to the inlet or to the return to tank line.
I spent some time at Climax Moly mine running some temp tests on the hydraulic system on the 475 fleet they had at that time. Climax was a cold place in Jan.
I spent some time at Climax Moly mine running some temp tests on the hydraulic system on the 475 fleet they had at that time. Climax was a cold place in Jan.
oldseabee
Senior Member
I forgot to mention when you are revving up to clear trash out of the relief valve on the pump to bottom out the bucket roll back a couple of times to bump the pressure up.
Dec. 1990 to May 1991 I was in the desert in Saudi Arabia as a mechanic with the Navy Seabees camping out in a ten man tent at night and during the day traveled around to different job sites in a 5 ton wrecker/service truck with another guy riding shotgun, no radio or cell phone to know what was going on or if we got into a fight no way to get help, but we did OK I was the equipment guy and my buddy was a truck mechanic.
Dec. 1990 to May 1991 I was in the desert in Saudi Arabia as a mechanic with the Navy Seabees camping out in a ten man tent at night and during the day traveled around to different job sites in a 5 ton wrecker/service truck with another guy riding shotgun, no radio or cell phone to know what was going on or if we got into a fight no way to get help, but we did OK I was the equipment guy and my buddy was a truck mechanic.
Yeah the Henderson mine and climax are set to shutdown again I heard the other day. They are running all the new stuff now. Letourneu and cats but it's cold in leadville in January lol. But back to my pumps the upper pump in my video..... That fitting I pointed at is the one I should see a pressure drop off in yes?
oldseabee
Senior Member
That's the one, it should measure the pressure in the front section of the pump, pressure should climb until it reaches the 1800 PSI point or close then should drop off as the control spool shifts and the front section of the pump stops sending oil to the main valve. The oil from the front section of the pump is redirected back to the inlet side of the pump.
oldseabee
Senior Member
I may have missed a question I should have asked. Any chance somebody not knowing what they were doing set that relief valve on the pump to a higher level above the main relief in the main valve so it will never switch and drop the front section of the pump. Try backing off the relief on the pump 2 or 3 turns or even lower to make sure that it is set low enough to shift,if that is the case then set it back to 1800 PSI.
I went back to your first post and seems like this machine is new to you, but I wasn't sure if the problem was already there or if it showed up after had been running it for some time.
Just a reminder, you should be above 1200 RPM for it to shift.
I went back to your first post and seems like this machine is new to you, but I wasn't sure if the problem was already there or if it showed up after had been running it for some time.
Just a reminder, you should be above 1200 RPM for it to shift.
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alright well thanks to you I know where my problem is Im sure its a stuck spool or something is adjusted way wrong. hard telling what someone did to an old loader trying to make it do something. On my 55b someone took on of the regulator valve springs out of the housing for the transmission oil pressure no wonder all i had was 160 psi of clutch pressure lol put the right spring in a boom perfect pressures everywhere cooler in and out ect.
Seabee what is your real name? feels like I should know it by now.
Seabee what is your real name? feels like I should know it by now.
oldseabee
Senior Member
Bill Dempsey, I am too old and to many health problems to be working any place. I do enjoy helping folks out with some of the old machines. My theory is that Knowledge is wasted if it's not shared, I kept most of the manuals and notes I accumulated over the years both on Clark and Bell equipment out of South Africa, they built logging equipment and artic dump trucks, I was National Service Manager and then VP of Product Support for USA, 23 years at Clark both engineering and regional Service Manager, 9 years at Bell.
I also go on a forestry forum and try to help out there. Keeps my mind active.
I also go on a forestry forum and try to help out there. Keeps my mind active.
oldseabee
Senior Member
Just wondering if you ever got your 275 working right. Hope I haven't led you astray.
Bill, I pulled the plug on top of that upper pump this morning. The spool seems to be free. There is a small crack in what looks like some sort of relief washer attached to the spool but it appears to be very insignificant. I have not tried to back off the adjusting screw yet. Hydraulic oil cooler in the radiator cracked so the radiator is currently out of the machine being repaired. Maybe there is a connection between the hydraulic oil cooler being cracked and something with this relief deal?