John is a friend with a D9G. He has made his living with the same tractor for years. He's now 68 and is still going strong. Good guy. He has done his own mechanic work on the tractor and has it in good shape. This hydraulic problem has him pulling his hair. He was pushing dirt, stripping at a quarry. The blade would not pick up. He finally got it picked up a foot or so and got the dozer where he could work on it. The blade doesn't settle. He replaced the hydraulic pump. He took off the hydraulic tank, looked for problems and found none apparent. He replaced the seals, and put new springs in the preasure release valve. Now it will lift the blade except when there is a load on it. Today we tapped into the up hydraulic line right before the cylinder with a gauge. The gauge read 5 or 6 hundred lifting up the blade. In operation the gauge never got higher than 1,000 psi. It would stay at that preasure with the lever fully engaged, the blade loaded with dirt and not rising. Couldn't really find anywhere else to tap for preasure. Any thoughts on this would be appreciated and passed on to John. Thanks Kent
zhkent, I hear you that the blade doesn't settle but I would cap off the lines to the blade lift cylinders and recheck the relief pressure at low engine speed and very carefully if the pump was replaced and the relief valve has been adjusted. You didn't indicate whether the blade is a straight blade or tilt blade, but some tilt blades have poppet valves/plungers in the lift cylinder pistons to equalize the blade lift cylinder stroke at full extension when the blade is pitched or tilted. If the poppets give trouble you can have problems getting the blade to lift.
Probably one of the quick drop valves at the top of one of the lift cylinders. Could be a pressure relief valve too. I had a tilt pump go out one time and it did funny things, since it controls pilot pressure. I would like to do what your friend does. So does he mostly do quarry work? How can a guy land a contract for such work, or reclaimation work. As a dozer owner operator?
Thanks for the response guys. Wulf, It's a semi U blade with tilt. It does have the poppets in the lift cylinder pistons. That's a good idea tapping off the lines. The darn tap is in the steel line between the hose connection and the quick drop valve. To block off at the quick drop valve would take a special fitting? Dozer 575, He installed a new tilt pump along with the regular pump. He put the new springs in the preasure release valve, looked it over and thought it looked ok. What would the symptoms of a bad quick drop valve be? (We cycled the blade a dozen times all the way up, then drop it, didn't make any change) (Quote) How can a guy land a contract for such work, or reclaimation work. As a dozer owner operator? (End Quote) John was raised about 5 miles from the quarry. His dad was in the business. He started operating young. If you want one of the best you call John. He had stripped a year or two for one quarry and a year or two for another one. He had done a lot of work for a local family on their ranch and farm and when one of them decided to start a quarry he figured on using John from the start. John was able to give him some info on how the other quarries had operated too. Also John is very efficient. He works by the hour. Ends up with a pretty low cost per yard. Thanks Kent
John took off the quickdrop valves. He did notice some damage in them. Kent
you check the hydraulic pressure on the ripper circuit .about 2200psi ,blades only 1400psi
John is definitely retired by now.
John Graham passed away about 2016, at home for lunch, sitting in his chair. He kept that dozer up in good shape and was using it till his death. He was good to me, taught me a lot, and is missed. He was not a big guy, but I never got my tracks cleaned out before he was done shoveling out the tracks on his tractor.
Thanks for the update. Sorry to hear about Mr. Graham. What happened to his D9G? Is She still pushing dirt in Kansas?
The family had an onsite auction of his things and it sold with another 9g, and his old Cat blade. He had 2 transfer tanks with a toolbox built on top. I bid up the first one, gave up, but got the second one. Was helping the family and when I went to load the one I'd gave up on it was full of fuel! I'd been up there a couple days and missed that. The dozers stayed local at that time. Not sure where they are now.