Hello i have a 1990 case 688p wheeled excavator but I have no swingbrake... where is The release valve located? Is The valve in The picture The release valve?
Good day & welcome to HEf Attached is an illustration of the swing valve sorry a little short of information with the 688. Kind regards Uffex
Yes thats is The swing valve ande The valve works But no swing brake
Good day When you post you have no swing brake, is it that you are referring to the slew/swing not stopping when you release the lever in either direction? The stopping of the slew/swing if like the 788 is made from the motor pressure, not a physical brake. The actual brake is much the same as an automobile hand brake. It can help a lot if you have a hydraulic schematic. Kind regards Uffex
Yes i have no swing brake so it does not stop turning if working on not lever ground
Good day Tomas If the swing motor is the same as the one I posted and the swing/slew will not stop in either direction, the most probable cause is a failed check valve in the head of the motor. A good check to make is to install a pressure gauge to the main line to see what level of pressure you have. Kind regards Uffex
At it again now... it does brake The swing but only after it has swung like 1-2meters....
Good day Tomas Please see attached. Kind regards Uffex
It is not weak at all in The swing.. just a major delar in The swing brake
Good day Tomas The information is relative to the problem, you can see what is involved to measure the braking distance. The last page gives some detail of possible cause of the issues. Kind regards Uffex
If I am sitting on almost lever ground and turn to The left... and then stop swinging it Will fall to The right just maybe 20 degred before stopping
I´m a good mechanic but new to hyrdaulics, maybe if a post a picture of the turning hydraulic engine U can mark what i should look on?
Good day Tomas Please post a photo I will try to help out. Kind regards Uffex
I hope The pictures i have taken makes some sence
Hi Tomas Not so easy can you see any label maybe Poclain Kind regards Uffex
Hi Tomas Take a look at the attached it shows the slew motor most of the photo's are of the slewing valve. Kind regards Uffex
Then this should be The swing brake release valve then....
Good day Tomas This illustrates the head of the slewing motor, which if my 766 information is correct has four valves, two relief and two check valves. Any one of these that leak will cause lack of braking in one direction only. The relief valves can be switched to determine if these move the issue from one side to the other. The check valves have to be removed and inspected. I do not have a schematic - manual for your machine, if you have one please post this I can then make better information. Kind regards Uffex
Braking is by hydraulic resistance, the brake valve should be regarded as a park brake as you regard the park brake of the car. Kind regards Uffex
Ok but it is The park brake on The swing i find not operation...
But on your picture it says swing brake valve.. u mean park brake for the swing? Anf that is just what i find not really working
This is The best pucture i have of the swing drive
Good day Tomas You are not the only guy to be confused by the term slew brake. When you move the control lever to slew left or right, the pressure from the lever releases the brake. When you return the lever to the neutral position after a short delay, the brake applies to hold the superstructure in the chosen position. The brake has absolutely nothing to do with stopping the machine. The slew motor has the possibility to generate pressure when the lever is in the neutral position and inertia drives the slew transmission. The motor reacts in just the same way as a pump, it is the pressure generation that the hydraulics use to stop the slewing process pumping the fluid against one of the relief valves in the head of the motor.We do not have skype. Kind regards Uffex
ok, it is the function that locks the superstructure thas is slow to react,,, the structure can glide so the buckets swisng 1-2 meters extra before it stops.... digging mud mowing to left stopping,, then the structure continues to move maybe 25 degrees atleast before it stops,,, hard to hit the correct stockpile when the machine will not stop the swinging,, trying to ccompensetate by turning left again does not help it wills till move 25 degres before stopping even though it moves slowly,,,, so the swing will brake and slow down when i let go of the control,, but it will not stop and lock where/when it should.... or am i thinking wrong? is the problem that it does not brake like it should so the upper structuire continues to move to long before the lock brake aplies? i will try to take more photos today of the swing motor and maybe U CAN HELP ME LOKALISE THE RELEIF VALVES ON IT.... sorry caps.. if those valves are worn out seating badly or badly udjested
Good day Tomas I need to be sure of the problem, would you please measure the swing braking accorrding to the attachment in both directions. Once I have that back from you I can be sure I am giving you good advice. Kind regards Uffex
ok i will do this, but i can tell u right now that if i´m turing it really slow it takes atlest 25 degres to stop but i will test full sped turn and se what happens
mostly i think i remeber it to be that it will drift to the ight side, even if i have been turning to the left,,, it will start drifting right....
Tested the machine now. It brakes... but slwus drift to The right a bit before locking. Same distanse even if u turn left or right.. but I think it takes to long time for The lock to engage...
Good day Tomas I gather from your post that the machine brakes within tolerance but when it comes to rest the parking brake fails to apply. If this is the case, the application of the park brake will be either the X port line is not draining or the brake is worn out. I would suggest you install a gauge on the X port of the brake checking that the pressure drains as it should. Keep in mind I have been working from a 788 hydraulic schematic. if you have a parts book or repair manual this would enable me to give more detailed advice. Kind regards Uffex
the parking brake locks it,,, but it takes time ebefore it does,,, maybe 2 seconds,,, if i swing and stop the siwing it brakes,, but hten it starts moving again before it locks mayve it is me not used to a 360 swinging digger i have had obnly backhoes beofre with hydraulic pistons swinging the boom left to right and maybe this machine brakes but not god enough when grpund ha a slight lean,,, we are about a yard,, but it leans to water will drain from it,, not a heavy lean but it leans,
Hi Tomas The brake is delayed on all machines. If the brake applied immediately this would cause damage to the slew transmission, two seconds does not seem so bad to me. Kind regards Uffex
ok,,, but could the proble be the reliof valves braking it as they should but not holding it,,,, ir just hat i´m used to piston hydraulic wich stops direct when u stop the boom swing.... this has not been a problem really when digging but i was onloading some beams the other day with it and i was terribly affarid to have the bucket hit the transporting car,,, i hade to swop the swing like 50cm before i wanted it to be so it would park in the correct space, i was alone it was dark outside... so hade to leav the cab to hook the lifting slings upp...
Hi Tomas While I can appreciate your circumstances from your posts I suspect you do not have a fault to address. Normally a machine slewing to set position is a question of judgment. I do not know of any excavator that will stop slewing without a delay. Kind regards Uffex
ok many thanx for help and support,,,, it is problay me who is used to digging with a backhoe that is used to swing stopping imedealty,,,