Hello All, Please help. I have an older Skytrak 8042. I want to say its a 1996. Everything runs great but i have this intermediate problem around 50% of the time i drive it. When driving in first gear it will go out of gear then it will pop back in gear.(de-clutching i think). In second gear the problem is worst as in it will not go back in gear as much. When im having this problem if i operate the boom up and down while im driving it operates fine. Stop operating the boom the forklift de-clutches. The other 50% of the time it works perfectly. Thanks in advance for your help.
Not sure what transmission those have , but have you checked the fluid level?
I have to prior SN 9909 transmission. I have checked then changed the transmission fluid and filter. With the same intermediate problem still there.
What's your machine serial number? We need that to troubleshoot the machine. I'll be glad to try to help. Some transmissions are checked idling and it could be starving for oil. If electric shift a relay or pressure switch could be bad.
I get the serial number this weekend. Im not around the machine right now.
OK
Tell me this-does it have an electric shifter that you rotate the knob to change gears or is it two levers on the dash?
2 levers on the dash its an older model
There is a screen on the suction pipe on some of those that can get clogged up. I'll need to know the transmission to be certain though. Also-did you check the oil level idling? On a Clark tranny it makes a big difference. Low oil level or a stopped up screen will cause the problem you have. Does it have a switch for the parking brake or is it manual?
Oil level while idling is good. I did not check the screen. Ill check and clean the screen this weekend. It has an electrical switch for the parking break.
I ordered the screen and gasket right after my message yesterday. Not sure if it will come in on time to do it this weekend but i will get the SN for you this weekend.
Does it have a transmission disconnect switch? By that I mean a toggle switch that when you engage it and step on the brake the transmission kicks out of gear-let up on the brake and it goes back in gear. Also a picture of the tranny and one of the ID plate on the tranny would be helpful,
The Serial Number is 5375 Sorry i just received your message. Ill have to get the tranny info this coming weekend. The screen should come in today so i will install it this weekend.
We have an older 8042, it is doing the same thing with the exemption that it run fine until I turn the wheels deep, let the boom down, retract boom, or tilt boom forward. Moving straight, raising boom, extending boom, or tilting back, everything runs fine. This is a manual machine with toggle switch park break, and 2 shift levers in the dash. Thanks for any help
ok we have the same machine with close and maybe the same problem. Mine also starts acting up with the wheels turned fully. Ill keep you posted if the screen fixes it.
Ok I checked the screen and it looked new. I installed the new one just because i had it but the same problem is still present.
Any update on if this machine is good now? I have same problem
What's yours doing?
jjolives29, Wow it has been 4 years since i started looking for solutions to these problem. My machine still does the same thing but not as often. Tractormech, If you could shed some light on the above problem D-clutch problem that would be amazing. I currently have the machine all apart replacing all hydraulic seals and 3 new rods. This machine also starts going really slow ( low flow rate) on all functions after around 2 hours of use. I can still pickup 7k lbs but the lift is very slow. after cool down it acks fine again. I did install all the test ports. On test port 1 the manual states (With engine at idle fully retract boom extend cylinder and hold. Check pump maximum pressure.) acceptance criteria is 2950psi but the highest i could achieve is 2500psi. the pump is original and the pressure adjustment was screwed all the way in. I have ordered a new pump.
Sent you a pm
What ended up being the solution. I have one with the same issue. Drive cuts in and out but seems to work consistently while using the boom lift/lower functions. The declutch has been inspected. fluids and screen are all ok. followed the hose on the declutch to the pressure reducing valve under the cab. was going to start checking hydraulic pressures from there but figured id check here first. Any help would be great. Serial # is prior to SN 9909. Unit has a Clark Transmisson.
The forklift has been unoperational for a while. I had a pump failure. I just finished replacing the main hydraulic pump/ re-sealing the cylinders and replacing a few rods. I just finished purging the air out of the cylinders and new lines yesterday. But to answer your question i still have the de clutch problem. after talking with a few people about this issue. The first thing i will try is to monitor the declutch pressure with my test gauge. It seems to be leakage on the de clutch circuit causing the issue. If that is the case it will be a valve rebuild job. But i have not tested it yet, its just the next step.
Thanks for the update. The conclusion ive come to is that the valve that is in the manifold under the cab is passing oil. When the park brake switch is in the off position, i have about 60 PSI supplied to the de-clutch and i believe that number should be 0psi. When i went to order the valve assembly, part #8036243, it shows discontinued. For the time being i just put a cap on the hose that goes to the de-clutch. Only change ive noticed so far is that the machine will go into gear with the park brake engaged. So ill have to pay more attention to that so that i don't drive through the brake.
As I recall about those machines, there is a dash switch that selects declutch with brake application. That lets you rev up the engine while stepping on the brake to lift the boom quickly, etc. without putting it in neutral. Perhaps the switch or brake sensor is malfunctioning and commanding a declutch?
GE all. We have been monitoring the forum and we may have come across the same issue with slow functionality (Low Flow rate). Seems like the only one to have mentioned this issue was @Skytrak Jake . Does anyone have a service manual or specifications that can be referenced for this model/ year sky Trak (Year 96/ Model 8042). We have resealed the pump to start with and have adjusted RPMs to compensate for the worn-out pump. Functionality has gotten better/ faster, but we do not have a spec to reference. What we're looking for is some kind of spec to reference for flowrate @Idle and or function speed specifications? Thanks, for the help.
SOLUTION! @TechSavy @mdraper Finally, I took the time to troubleshoot the machine. I added the rest of the ports to quick connect gauges. My machine also had slow functions and it seemed to bog down the engine when I would operate functions or fully lock the wheels, one direction or another. The brake (transmission) should be 500psi and the de clutch (fitting on the transmission between where the shift cables enter the transmission) should be 0psi when the brake switch is disengaged. When engaged the brake should be 0psi and the declutch should be 500psi. The brake and declutch are connected to the A and B ports of same valve so you can test either. When I tested the declutch it function correctly until I touched the steering wheel. Then it was 200psi when 0 should be and 800psi when 500 should be. Then I took the return from this valve off. It is the 3/8 hose with a 90 and it connected to the bottom of the priority valve. I then routed it to a bucket. I turned the machine on with the electric brake switch next to the steering wheel in the disengaged position, which should be 0 psi on the de clutch. Vary minimum flow should have came through that port. I turned on the machine and within 10 seconds I had to turn it off because I almost filled up a 5 gallon bucket with tank returns from that 3/8ths hose. It was shooting out the hose. I was pretty sure it was the pressure reducing valve underneath the operator seat floor. I ordered a new valve part number 8032993 (google it they are available for $110) I received it in today. When I pulled out the old valve, it didn’t have any O-rings or back up rings installed. I guess the hydraulic flow has been rushing past it for so long that it completely cleaned off any trace of O-ring or backer ring. The port where the cartridge valve installed to still looked in great condition. When I turned on the machine, it was like I was driving a brand new machine. All sluggish issues were fixed due to the vast reduction of hydraulic flow running through the system. It drives forward and reverse in all gears with ease. All functions have picked up speed. No matter which function I deadhead the engine doesn’t even come close to bogging down now. PS I did put a new model Skytrack pump into the machine since the original pumps are discontinued, which required some machining and some adapters and all new hoses but it works great. It took around $6200 for the pump retrofit with all machining work being free. Replacing the pump did not solve the problem as I originally hoped. Here are a few pictures of the bracket I made and the new style pump installed. I did test out my original pump and it wasn’t the problem. It still works great but the original pump is discontinued and they don’t sell rebuild kits for it. I will stick with my new pump, but if someone wants a spare pump for their machine, I’ll be happy to sell my original pump for good price.
Here’s a picture of the new Partridge installed onto the valve block to show where it is installed.