Good morning I hope some of you can help me. Have a 307 b 6kz that will barely travel. If hold the boom lever and let it bottom out travels fine but this gets very irritating laying pipe. Swivel seals are new. Tracks fine while holding boom so I don't suspect straight travel valve. Did find broken wires to power up solenoid valve checked for proper voltage and repaired. I have read there is a calibration procedure for these machines. If any one could help I would be most thankful.
is it just the boom that will allow it to travel faster or will other functions give the same result Mark
The only two I have tried is bucket and boom. Yes the bucket helps but it isn't as effective as the boom.
I had an E70B that did the same thing and it turned out to be the pressure relief valve. The lock nut on it had gotten loose and allowed the valve to back off.
Hi it sounds like you have a shuttle valve issue (resolver Valve) on the last one in the signal line. tee into the signal line going to the pump controller and check pressure as you operate each control. maximum pressure in this circuit is 500psi. mark
Ok I will look at this tomorrow. Where do I tee into this signal line. I have only a block diagram of system.
at the pump controller is easiest to get to and is closest to the pump control
I haven't yet checked this signal line as I was in process of checking relief pressures. Following the procedure to set the main for travel it will not each the recommended pressure of 4400 even bottoming out pressure adjustment it only reaches 3200 and will surge higher as relief cycles. As far as implement pressure it adjusts as noted to 4000. No trash in valve no broken springs. What would cause this main to relieve and not build necessary pressure? If anyone has a schematic it would be great. Thanks
main relief valve setting is increased by a selector valve that allows pilot pressure to be directed to the top of the main relief valve. this pressure acts on a small piston in relief valve and compress the main relief valve spring to increase pressure setting for travel
Thanks for the print I see why you said to checkshuttle valves will finish this tomorrow. I'll post my finding later
Just want to make sure I'm seeing the correct fitting to t into. Looking from back of machine there are five small lines. One is from reducing valve one goes to control manifold and one ties back to supply. That leaves one small line on bottom left and on on bottom right that has a gauge port on it. Just want to make sure which is signal line
Ok I have tee'd into signal line and checked pressure at every operation pressures range 510 to 520. Also tied in and checked power solenoid. It is around 560. Same for track speed solenoid. Checked control valve pressure at specified gauge port it is 500. Again only getting 3000-3200 out of pump port with left travel fully depressed in either direction. Same port bucket curl is at 4100. Per spec track psi should be 4475. What in this circuit would dump to prevent pressure rise? First thought were relief valves but they look good (main). Again other functions are good. Thanks
What about straight travel valve or selector?
when travelling with other circuit engaged, travel valve moves and only one pump is used to drive travel motors. you stated that the left travel circuit will not build to the correct pressure. are you saying that the right trave circuit is OK? if so you could have a problem with one pump or the swivel is bypassing still or a weak travel motor 1/if there is enough length in the main hoses on the pump swap them around and re check 2/block off main hoses going to swivel and recheck 3/check case drain flow on travel motors ,if you don't have spec for that compare one side to the other Mark
Sorry for any confusion. Both tracks are weak. My stating of pressures was from following cats main relief valve pressure check and adjust procedure. On first adjustment it never reaches the 4500 but on the second it adjusts to the 4100 easily I know this can't be correct with the first pressure being incorrect. I was only given partial info. The boom is also weak. Going to check cylinder bypass tomorrow just to rule out internal leaks for boom. But you can visually see it drifting with load. Also the boom and stick controls were reversed years ago by cat. This was done on the connection manifold underneath. I know power solenoid working you can visually see machine speed up and slow down when it is operated while traveling with boom lever held. Track speed makes no change. I know solenoid working. As far as swivels I was very careful as I have built hundreds of valves and cylinders. Not saying a screw up impossible. But I will plug lines tomorrow at swivel see if can see change in pressure. Thanks sorry to ramble but all help appreciated so trying to be complete with info
hi I would still swap the main pump out put hoses over and see if problem moves
Ok swapped hoses same problem. As I am doing this as a favor I took machine out of shop today to see for myself what is or isn't doing. If I only try to tram right track it really doesn't move at all. Can not hear pump load. Left track if hold it for a couple seconds pump will load somewhat and track will move. Pull both tracks simultaneously and both move but pump still not loaded. Add another function such as boom up and pump loads and both tracks work as they should. I think this in my mind should eliminate from swivel down. Going to look at signal lines again and make sure I was on the correct line. Any ideas? Thanks
Okay hooked pressure line to right and left pump and worked tracks accordingly. Both tracks only building around 1800 psi. All other implements hit 4000 without issue. Pump is not loading correctly for travel. The reading I gave in previous message was with signal line to relief capped and plugged. Today's is in operational state No pump load.
Ok went further attached pressure gauge to control fitting on track valve left side building little over 100 in reverse less in forward right side barely flutters needle past 75. Removed bottom of cab checked control pressure entering foot valve 500 psi checked on out going same readings as on top of directional valves. Looks to not be getting pump control pressure through valve
Do you have the ability to monitor both pumps simultaneously ? left track and right track use P1 & P2 differently, but if the 2 are shared via straight line travel pedal , you would want to remove the pedal as a possible parasite to the LS signal. Simply mark them up and cap them off. Since you stated certain functions are weak , which ones? Are they specific to one joystick or the other? Look for common denominators, are all the functions hurting on the same side of the valve? Are you receiving the same signals to each pump to stroke up? What if you were to pin the sprockets t the car body, can you reach maximum pressure for travel? Raise left track off ground, paint a pad . at full throttle run the track full stoke record your pressure in rabbit and turtle . Time 3 revolutions of the track and compare left to right. Forward and reverse. Does the machine have an option fitted? Hammer shear compactor etc? Loads of stuff all at once I know, but info in , info out.
reread above post, try capping off and marking straight line travel valve to effectively remove as possible loss of control pressure.
still sounds like signal problem as my first post I think you need to recheck
Rechecked pilot pressure coming from safety valve to travel control valve. 500 psi. Removed lines from travel control valve and put gauges in them very little pressure. Took left track lines off and installed on boom swing control valve. Track is alive and well. Next took right track lines and hooked to boom swing valve right track also alive and well. This should prove the rest of travel circuit if I'm seeing this correctly by just swapping to another pilot control valve this still uses same shuttle valves directional and relief. Think I will pull foot valve and see if it is servicable
But yes you are correct I started checking at pump for signal pressure and as I didn't have it I started walking back up the line checking for it and that is when I found it's not coming through valve assembly. Print seems to show some type of in line strainer or filter coming into valve block hopefully I find where piece of hose has created obstruction.
You've proven your track motors and turning joint are unharmed. Have you deadheaded your signal lines into a gauge from the servo control? Most servo levers have a filtered inlet fitting. So from your safety solenoid going to the manifold which feeds L,R and straight line travel pedals, check that fitting for debris/obstruction. Check pressure coming out of that manifold going to each respective valve. If you straight line, does it track straight, do both pumps come on line? Have you checked travel pressure L&R fwd& back on pump1&2? With the tracks stalled/pinned?
Yes I pinned the tracks in the beginning to check main relief pressure. And after I posted last I went back and recheckedpressures through servo or pilot valve. 500 coming into valve deadheaded outlet for travel into guage only 125 psi. Checked inlet strainer for debris found nothing. Again when hooking the tracks on at a time to swing boom controlvalve (pedal)which aside from the cushion action is ported identically each track works as should. Lao stated boom issues earlier but boom has internal leakage from piston side to rod side causing the reduction in lifting capability. But I would think that I should have had full pilot pressure at port instead of only a portion. The right track has not turned when only pulling handle in years but worked without hesitation on swing boom valve. Could work it slow or fast. Same with left. I have pulled the valve to disassemble to look for problems
Have you removed the straight line travel pedal from the equation. It has the possibility to drain your control pressure to tank . You've proven your travel motors are somewhat capable, what you haven't found is where your control pressure is dumping to tank. By eliminating STP you have isolated control to left and right. No commonality except through center passage in MCV. Good luck, keep us posted, please. BTW, what valve are you inspecting?
Having unhooked the lines from the bottom of the pedals (pilot control ) I hooked gauges one at a time where these lines going to manifold valve hook. Only 125 psi of control pressure dead headed into guage through pedal valve for travel. Should be 500 at full handle/pedal stroke. I think it's more not getting it than losing it
But as a final check I will isolate Stv tomorrow. And as my left pedal was seeping fluid I am going to reseal if possible. Thank you for your continued help. I have many years industrial hydraulic experience but not as much with mobile. Very similar but some differences. I am more accustomed to 0-10 volt signals and proportional feedback systems. But this will be solved
And both pumps came online in straight line travel? Do you have enough control line to borrow servo from a neighboring spool? You've ran the function off a different spool. Let's change servo control. It sucks cuz you have to do both A&B for 2 functions, but can't be any worse than swapping banks as you've already done.
Did you check all the shuttle valves at the servo control feed manifold? There's 3 of them there , make sure each has a shuttle ball in place and that the seats aren't damaged. In the schematic you provided it would be item 19 in the bottom left corner And to clarify , you have 500 psi at "E3" what about going into pedals at TLA1&2 & TRA1&2