CAT 345CL PJW The swing brake releases when traveling and digging when it shouldn't release. If not moving and swing right or left the brake functions properly. When traveling brake releases and when digging also. Any help would be appreciated.
Look to see if switch #24 has been turned on.
good call Mark. i have used that switch but forgot about it.
It is supposed to release anytime a function is used. It only sets when all the functions are not used for several seconds.
when fine swing is switched on the brake stays released at all times. When I switch to manual mode the brake stays locked on and house will not swing. The only time the brake functions properly is standing still. The brake should not release while digging unless you attempt swing or release while travel
As a first step put a pressure gauge into the swing brake and see if the pressure reduces to zero at all times when the brakre should be applied.? Pilot pressure releases the brake. Failing that pull the electrical connector on the swing brake solenoid valve. That should mean that the brake will not release at all. Is there a possibility that someone has been messing with the swing brake solenoid valve adjustment screw..?
I'm thinking you are going to have to show me something in an operator's manual that says how that works. Swing brakes are only for parking the house in place. So school me on this one.
In normal use the swing brake should apply after a couple of seconds of no swing command. When the fine swing switch is activated the swing brake is off all the time. In practice this means that the swing will drift.
IIRC, the swing brake releases anytime upper functions are activated, even travel. Or, when in fine swing. Pull out the makeup valves (all the valves) on the swing motors and find the blown seals. They'll all be threaded in cartridges. Basically, oil is stovepiped into the swing motors to hold the house when the brakes are released. It's deadheaded oil that prevents rotation when brake is off. IIRC, the brake is reapplied 7 seconds after upper functions have been deactivated. These guys ... Oh, and relieve the hydraulic tank pressure first, as the tank is charged via engine boost. What's a fair price for used oem service manuals? I traded my PJW away when the slippers came off the pistons in pump #2 @ 5800hrs, and Cat's Service Letter no longer applied (too many years past expiration).
I put a gauge on the brake pilot line and it releases on every function but if stationary the swing brakes properly when lever is released as long as no other function is being used like loading a truck. So i tried swapping the 2 pressure switches on the main valve and then it did not release on travel but stayed released on all other functions but did not brake when stationary. I installed a new solenoid to rule that out. I'll try pulling the connector to see what happens. I think it's an electrical problem.
Bear in mind that there is a 6-1/2 second delay programmed into the electronic system between putting the swing control joystick in the neutral position and the ECM de-energizing the swing brake solenoid valve to apply the brake. Don’t ask me why it’s that number, that’s just what the manual says.
Then it appears to be working correctly. I am new to the 345, I operate 320, 312, 307 every day and they do not function that way. When you stop swing over a dump truck the machine needs to stop immediately. There has to be a way to adjust this. Do the manuals for the smaller machines stop immediately ? Thank you for your help.
I am not an operator but I know the basics of running a machine of this size class. Is it not usual when truck loading to stop the swing by “counter-slewing”.? In other words giving the swing joystick a twitch in the opposite direction to the one the machine is swinging in order to bring the upper frame to a stop. The way I read the swing system operation related to the brake is that the delay I referred to above is programmed into the software and is not adjustable. I will get a copy of it and post it up. EDITA: Swing Brake Solenoid The swing brake solenoid is an output of the Hydraulic Pump ECM. The swing brake solenoid is energized in order to release the swing brake. The swing brake solenoid is de-energized approximately 6.5 seconds after ANY control lever is moved to NEUTRAL position, except the travel levers/pedals.
All these machines have the same brake application delay . This tells me there’s something else causing your problem like a leaky relief or failing swing motor.
It's clearly unsafe to have that delay. 6.5 seconds is a very long time to stop swing. The 320's that I run do not have that delay.
The brakes do not stop the house from turning. They only hold the house in place when the machine is not being used. People are trying to tell you that the hydraulics hold the house while the machine is operating. Large machines have carry on when swinging because of the length of the boom and stick and the weight of the material in the bucket. A properly operating swing system in an excavator that hasn't been modified will naturally stop swinging when you let go of the control. None of them will stop instantly. You either have a problem in the swing motor or you haven't gotten used to the characteristics of this particular machine. From the sounds of your posts, you haven't read the operation and maintenance manual.
Sounds more like excessive drift caused by worn motor or relief valves etc. If you swing the machine at full speed and release level to stop swing at 12 ó clock position what position does it stop at?
Think of it this way. With the interia of all the moving parts in a machine of that size when swinging with a loaded bucket, if the swing brake applied fully as soon as the joystick was returned to the neutral position something in the swing system (e.g. swing motor, gearbox, swing pinion) would go bang PDQ.
You're missing something. Swing function is stopped by shutting off the oil, resulting in trapped pressure. The same trapped pressure prevents movement when the brakes is released. Your trapped oil is escaping. The 320 is the exact same setup, sans the 2nd swing drive.
It makes sense that swing is not going to stop by brake, rather it should stop naturally then brake apply. Would oil pressure in the motors help that natural slowing ? I think the main seals in the bottom of the swing motors are blown because I get hydro oil leak from center of machine at bottom and have been planning on pulling motors and checking / changing seals. I'm also going to do something I never thought of, try reading the manual !
I don't know if you saw my last post, I suppose a leaky main seal on the swing motors would lose that pressure.....
Oil pressure in motor head is the only thing slowing down the swing. If the bottom seals are blown in motor its probably caused by too much oil bypassing inside motor causing bottom seals to blow. Please read the manual before you hurt yourself or your wallet
The leaking seal is not causing your swing to drift. But the problem that's allowing the drift is probably what caused the seal to blow
where might the oil be bypassing
I will check these seals first, a lot easier than pulling motors
Cut open and dissect the two case drain filters. If there is swing motor integrity issue, there'll be debris in the case drain filters.
Just to update, I resealed the relief valves, no luck. Pulled the motors and resealed, There was also a couple things out of place, the top valve plate was a bit skewed, 1 friction plate, and 1 of the spacers on the sun gear at the top of swing drive. Put it back together and works perfect, stops nicely when control is released. Before I got it, the machine died and the guy told me he loosened up the top of the swing motors to release brake and clock the house to get in on trailer. I think when he socked the top of the motors back down some things were out of place. Thanks for all the help.