We have a 97 816F, in freezing temperature it will sometimes not move. The wheels are free, not frozen to the ground or around the axle. All that cat gave me info wise was to make sure im using sae 30 fluid. When i engage the tranny, the machine will lurch slightly like its inn gear, both forward and reverse, but won't go anywhere. In a milder cold it will eventually break free, but if its super cold sometimes i can't get it to move at all, any ideas? Thanks in advance
I can feel your COLD. Drain the diff's a little and make sure they have no water in them that can freeze and lock the gears up. What kind of trans? cable shift, electric over hyd shift ICM solinoids. I take it the torque is under load anytime it will not move. Later Bob
I would assume the diffs are fine as it was just in for service not too long ago. Its electric shift, not cable. Never have this prob in warmer months. I will check the diffs tomorrow. Somebody mentioned today that it sounds to them that the fluids are too cold. Today it was -25c in the morning, machine was plugged in all night. Fitted it up when i got in. It took about three hours for it to finally break free. Yes when it doesn't move i can see the torque converter guage climb. On a side note, lately the parking brake lever wont budge until thhe machine has thoroughly warmed up. I have left it off overnight since it got cold so i won't run into any problems with it (if the machine gets really warm the parkinng brake will engage itself while the machine is moving, which usually ends up with me smashing into the windshield....)
Fired it up not fitted....
You just told me a lot Faraday. Parking brake Dynamiteing while driving warm. Solve that problem and you got it fixed. I have a feeling the brake accumulator pressure holds the parking brake off/released. If so you have a brake oil pressure problem. Check out accumulator charging valve. Cut in and cut out pressures, Can't Adjust so replace valve if not right. Also check accumulator charge with no oil in them. Later Bob
To further this, last year we had the brake accumulators checked, one was replaced. We also had the whole parkinng brake valve assembly (not sure if thsts exactly what its called) replaced but it still happens. Ive only been working with this machine for 3 years, but ive been told that this problem has been going on for a lot longer than that. Does this info make any sense or change anything?
Also i did say that i don't leave the parking brake engaged overnight, so it cant be that the brake is stuck on can it? From what i gather yhe accumulator just retains a charge so that if there is a broken line etc u have a few pumps before the brakes are gone completely, or is my info wrong....
Check accumulator charge, run mach untill acc is charged park brake released. Shut off eng and turn key back on. Pump peddal and count applications untill low brake pressure light comes on, should be 5 or more. Later Bob
Thanks for the help, more info than cat was willing to offer...next you will tell me you work for them and i should eat my words.. Ill post my findings tomorrow. Thanks again
Another thing is that accumulators will slowly discharge overnight so leaving the park brake released may not be doing what you think it's doing. Does the low accumulator pressure light flash (or do you get any sort of warning for low accumulator pressure) when you first crank the machine up in the morning..? Just had a quick look at the Sys Op. The rear accumulator operates the rear service brakes & the park brake, the front one just the front service brakes.
Sorry for the wait, been snowin a lot, spent all day plowing not diagnosing. I let the machine run and when i shut it off i pressed the brakes once and a light came on. My manual is at the shop so i couldn't reference the light, nor find it on the net. It wasn't the parking brake light, it was the third one from the left. I will take a picture and post in a minute. The compactor did move this morning but again it was stuck for a bit of time. It really feels like its literally breaking free when it moves.
Tried to upload it, but im using my phone and its not working. The light looks like a circle with a dot in the centre and two arrows pointing at the centre. Outside the circle is two separate lines following the contour of the circle... If i was shown this symbol, the best way to describe it would resemble brake shoes. Not trying to influence any opinions.
You aren't influencing, just informing us Faraday. That light that looks like an old drum brake is your brake pressure indicator and should stay off for 5 or 6 applications after the engine is shut down. The accumulators should hold enough oil under pressure for those applications. One of two things could be wrong, accumulator not charged right or a big leak some place. To check for a leak at the brake pistons, look for a raising oil level in the axles. To check accumulator charge you need a gauge and hose with connector to go on brake pressure nipple. With engine off pump brakes untill connector will go on easily(see manual for loaction to check) Start engine and watch the pressure rise, the charging valve will cut out and pressure hold(write this pressure down), then pump the parking brake slowly and watch pressure drop untill it starts to rise again (write down this pressure too) You have recorded the cut out and cut in pressures, compare to manual spec. The charge valve is not adjustable, need to replace if bad. Now watch to see if accumulator will hold pressure with the engine off, if it does count the pumps untill gauge goes to zero. If the accumulator is charged you will notice the pressure drop every pump and then fall to zero. The pressure before the last pump is app the accumulator charge. This should get you started. Later Bob
Another point i should make is that i think only one of the accumulators were changed. If you stand on the entry side of the mschine and open the sccess to the tranny fill/ brake accumulators, the closest accumulator was the one that was changed, the second one wasn't. Any idea which one operates the back/parking brakes and which is the front?
Open the hinged panel behind the cab that contains the accumulators. The 2 accumulators are mounted on a firewall. As you are looking towards the firewall the front brake accumulator is the one on your left, the rear/park brake accumulator is the one on your right.
Should be in manual but you might be able to see where the hyd lines go from each. Another thing, I think you can only check the pressure on one system and the low pressure switch is also only on one system. You might get someone in to charge the accumulators, if you do make sure they keep pumping the brake as they charge them to get all of the oil out while the nitrogen is charged. Later Bob
Another thing to check, and I'm not totally sure if it's set up the same way but, there's 2 switches in the far left brake pedal assembly. One is for the brake light switch, the other is for the transmission neutralizer. Basically what could happen is if dirt builds up under the pedals, then freezes and expands over night it could be just enough to break the contacts in that switch. I know it happens to our loaders all the time, some operators know about it and some of the new guys don't. Another thing could be the if the alternator quits charging?