I have an AGS ser# CAT 345 that will not walk. When you push the pedals the tracks tension up but it doesn't move, if you keep the pedals pressed the motor lugs down and tries to stall. There is also a significant time lag when operating the two joysticks before the machine will operate and when it does there is no fine control. Has had MCV, swivel and pump pilot pump rebuilt in the last twelve months. Any idea's.
Check pilot pressure, also main pump pressures while machine is idling and while trying to make a movement. When was the last time it worked as supposed and did it have any work done to it then?
I agree with Per Eriksson I think you should check the pump pressure, it sounds to me like the pump is not stroking up. this could be due to a faulty valve plate not sliding correctly. Is it on both tracks? If you would like to talk check my website out and give me a call. upstatehydraulicdesign.com
Hello Steed6557, Have you opened the cover on the back of the tracks that covers the final drives? This can fill up with dirt over time and clog- I cleaned one out this week at work experience. Hope this helps!
Sounds like you need a good cleaning.
Does the travel alarm sound? Does it stall the tracks in both directions, one at a time or lifted off the ground? Does it travel using the straight travel pedal? How is it when you curl the bucked while traveling?
could be anything, is the rotary coupling leaking? I've had them bypass back to tank causing similar issues, sounds like pilot pressure may be down
Sorry for the delay, not using the machine obviously. We took the pump off and it had torn up the rotating groups. Put reman pump and pilot pump on and got CAT dealer out to re-do pressures. Machine still won't walk, CAT dealer changed MRV-seat was hammered-and still won't move. Pump is making 5k#, but is screaming from the top section mainly and there is a bad vibe through the machine when you load up the hydraulics. Very lazy on the control handles, you have to stroke them fully and wait before they will do anything. To get the boom to move you have to stroke another function and then it will move but the vibe is so bad you have to shut it down straight away. Any idea's? AGS01145, 345BL.
you seem to be having a main relief valve problem if the engine is stalling you got to take the pump pressure should be anout 5000psi. pilot should be 500psi
All pump pressures are ok as described in earlier post, also the main relief valve is new, the swivel has been re-sealed as has the main control valve.
How tight are the tracks? How is the rest of the hydraulic circuits working? If the pump is loading up enough to choke engine down it is most likely not a pump stroking or pressure problem. Do you have brake pressure down to the travel motors? It is the smallest line going to motors.
The screaming and vibration indicates that the pumps isn't getting enough oil and cavitates, is the suction line and screen inside the tank clean and unobstructed?
Thanks for the responses today, took the pins out of the brakes at the travel motors and it walks. If you read all of the posts you will see that the machine has a new pump, pilot pump, main relief valve, resealed main control valve. Put the pins back in and it won't walk, isolated the fan motor pump and still cavitates and vibrates I will check the screen again in the morning.
sounds as though the suction screen is blocked, doesnt sounds too good if theres metal floating around the system? have you checked for airation? is the oil milky looking?
Obviously check the tank suction screen first, but if there is some sort of flexible suction hose between the hydraulic tank and the pump inlet then check that hasn't collapsed internally causing lack of supply to the pump. It would give all the audible signs of cavitation. Picking up on your point above that if you take the pins out of the brakes it walks, are the brakes releasing correctly when everything's assembled correctly ........??
The screens are ok and will check the suction hose today. With the pins in the brakes it will not walk. Thanks.
I've been looking at the service manual for the procedure releasing the brakes in order to tow the machine. This procedure doesn't speak about any removing any sort of "pin" but instead requires the brake valve to be removed from the travel motor and the spring & spool removed from the brake valve. This is followed by the installation of a pair of M8 x 90 bolts & 9mm thickness of washers in 2 plug holes in the end of the travel motor, obviously after removing the plugs. Then the "modified" brake valve goes back on, connect up the lines, and the machine has no brakes. Is this what you are doing..? If it is and the machine will travel in this condition but not travel when the brake have to be released hydraulically then IMO you have to be looking at the hydraulic circuit to the brakes, maybe also in the centre swivel for an internal leak.
Can I suggest that you inspect the slow return check valve? Its bolted between the main control valve and the line to the hydraulic cooler. Part number 1850384 on your machine. Its a pain to get at. You'll need to drain the tank and you'll still lose a fair bit of oil but I've got a feeling it may be worthwhile.
did you have make correct connection and place your hydraulic lines ? I think it is important to re check all lines that you disconnect when you work reseal control valve and swivel
hi there is one or more hoses mixed up , more than likely on the pilot pump, if you need to know the way these are attached i can take photos. adirty gause wouldnt cause this, looks like the oil is going backways when you see all this sediment in oil also
Final disposition of this problem? I have a similar problem with an older 345 B (4ss sn), however I do not have the same PINS for releasing the brakes. Is there an easy way to release the spring tension placed on thebrake?