I purchased an older model 753 Bobcat ser#508614054. The lift and tilt work fine until I hook a grappler to the aux Hydraulics. I can open the jaws on the grappler but they will not close,and the lift and tilt stop operating. If I turn off the engine and re-start I regain my lift and tilt.
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It sounds like your aux is sticking when you open the grapple. The aux is going over relief which is causing the lift and tilt no to work. I would look at you thumb switch. Since it resets when you restart the unit, it is an electric problem.
Thanks for the info,it's a place to start. Do the thumb switches on both right and left operate the aux supply,or does only one . What I mean to say does one switch open flow,and the other close(or return the flow)? When I remove switch is it just snapped in or fastened some other way? Will look at it tomorrow,Thanks for the place to start.It sounds like your aux is sticking when you open the grapple. The aux is going over relief which is causing the lift and tilt no to work. I would look at you thumb switch. Since it resets when you restart the unit, it is an electric problem.
The switch is glued into the handle, not as simple as removing and replacing it.Thanks for the info,it's a place to start. Do the thumb switches on both right and left operate the aux supply,or does only one . What I mean to say does one switch open flow,and the other close(or return the flow)? When I remove switch is it just snapped in or fastened some other way? Will look at it tomorrow,Thanks for the place to start.
When you activate the aux hydraulics, what happens when you try and pull the coil off the stems? They should be pulling back at it.
Over time the stems stick inside, if the coils are good, and the switch makes the moth magnetize the issue is the stems.
How are the stems removed? After the coils are removed the hex nut at the base is turned out to remove the stem. Could they be sticking and not moving free? Would you clean with light emery paper? I don't have a repair manual as of yet. Looking for one ASAP. Thanks for the info.The switch is glued into the handle, not as simple as removing and replacing it.
When you activate the aux hydraulics, what happens when you try and pull the coil off the stems? They should be pulling back at it.
Over time the stems stick inside, if the coils are good, and the switch makes the moth magnetize the issue is the stems.
With the coils removed, they un-screw from the control block.How are the stems removed? After the coils are removed the hex nut at the base is turned out to remove the stem. Could they be sticking and not moving free? Would you clean with light emery paper? I don't have a repair manual as of yet. Looking for one ASAP. Thanks for the info.
If you swap the stems and the problem moves, it is the stem.
Do not touch them with emery paper.
If you confirm tha the stem is at fault, you can try and disassemble it to free it up.
Get a set of soft jaws for your vice or aluminium for between the jaws and the base of the stem. The part with the Orings. With it secured un-srew it with a spanner on the large hex 3/4" i think. With it open, you will need to pull all the innards out and make sure they move freely. The main parts that need to move is the plunger that the coil pulls and there is a small spool inside where the Orings are. They all need to move freely. Use compressed air and solvent to clean and assemble with oil.
I bought an S150 that had been sitting for a few months and one stem was stuck. I pulled it apart and did this, has not missed a beat since.
Just take note of how things came out so they go back in the same way. If it fails, the dealer can sell you a new one.
Thank you for the information. I will do as you sugest and see if that takes care of the problem. I will post when it's resolved.With the coils removed, they un-screw from the control block.
If you swap the stems and the problem moves, it is the stem.
Do not touch them with emery paper.
If you confirm tha the stem is at fault, you can try and disassemble it to free it up.
Get a set of soft jaws for your vice or aluminium for between the jaws and the base of the stem. The part with the Orings. With it secured un-srew it with a spanner on the large hex 3/4" i think. With it open, you will need to pull all the innards out and make sure they move freely. The main parts that need to move is the plunger that the coil pulls and there is a small spool inside where the Orings are. They all need to move freely. Use compressed air and solvent to clean and assemble with oil.
I bought an S150 that had been sitting for a few months and one stem was stuck. I pulled it apart and did this, has not missed a beat since.
Just take note of how things came out so they go back in the same way. If it fails, the dealer can sell you a new one.
I removed and cleaned BICS . All seemed clean and free. With the BICS off I ran power and ground to the coil and there is no movement to the valve in either of the 2 BICS. Shouldn't they work powering them this way?Thank you for the information. I will do as you sugest and see if that takes care of the problem. I will post when it's resolved.
How do I test the coils? I tried to put power to them and no luck. I don't want to take the switch apart before I know the coil is operating as it should. It has to be electrical....when I shut the engine down and re-start the tilt and lift work fine. it re-sets it self.... It locks up as soon as the aux switch is applied.I removed and cleaned BICS . All seemed clean and free. With the BICS off I ran power and ground to the coil and there is no movement to the valve in either of the 2 BICS. Shouldn't they work powering them this way?
If you use a meter on the coils, look for resistance.How do I test the coils? I tried to put power to them and no luck. I don't want to take the switch apart before I know the coil is operating as it should. It has to be electrical....when I shut the engine down and re-start the tilt and lift work fine. it re-sets it self.... It locks up as soon as the aux switch is applied.
With the engine running and aux engaged, there should be voltage at the connectors for the coils.
You should be able to apply power to the coils and feel the stems click lightly. Just don't keep them powered this way as they are not all 12v
I don't think your problem is the stem or the coil. It sounds like a power to the coil problem. The coil is staying energized, which is dead heading the grapple open causing you other hydraulic problem. Turning the key off deactivates the aux system. That is why your problem goes away until you try to use the aux again. I bet the centering spring is broke in the tumb switch and not working properly.If you use a meter on the coils, look for resistance.
With the engine running and aux engaged, there should be voltage at the connectors for the coils.
You should be able to apply power to the coils and feel the stems click lightly. Just don't keep them powered this way as they are not all 12v
Thank you both Bobcatdan,and Tazz....I traced the wires from the BICS to the hand levers and found a seris of splices in orange,black,and green wires...Someone jury-rigged the wiring previous to me.. I need to get the wiring diagram for this unit and don't know the year or model....The serial# is 508614054.. Where can I get a repair manual for this unit? One last question.....What do the BICS do and when are they open,and closed? Thanks again for your help........... THEOI don't think your problem is the stem or the coil. It sounds like a power to the coil problem. The coil is staying energized, which is dead heading the grapple open causing you other hydraulic problem. Turning the key off deactivates the aux system. That is why your problem goes away until you try to use the aux again. I bet the centering spring is broke in the tumb switch and not working properly.
BICS stands for bobcat interlock control system. It is a safety system that controls the brake and lift/ tilt lock systems. The aux is not controlled by BICS. That is a separate system with its own controller.Thank you both Bobcatdan,and Tazz....I traced the wires from the BICS to the hand levers and found a seris of splices in orange,black,and green wires...Someone jury-rigged the wiring previous to me.. I need to get the wiring diagram for this unit and don't know the year or model....The serial# is 508614054.. Where can I get a repair manual for this unit? One last question.....What do the BICS do and when are they open,and closed? Thanks again for your help........... THEO
Dan has a good point.BICS stands for bobcat interlock control system. It is a safety system that controls the brake and lift/ tilt lock systems. The aux is not controlled by BICS. That is a separate system with its own controller.
The splices you have seen, are any bare and possibly touching thengs they shouldn't?
There is a good possibility the reason this was done is the previous owner replaced the hand grips or handle. You need to remove the wires from the connector to do this, they may have been lazy and just cut it off.
I hope to get to the thumb switch,just not sure how to disassemble without breaking . Does the power run to the switch when the aux switch is on( green)? Anyone ever remove a thumb switch?Dan has a good point.
The splices you have seen, are any bare and possibly touching thengs they shouldn't?
There is a good possibility the reason this was done is the previous owner replaced the hand grips or handle. You need to remove the wires from the connector to do this, they may have been lazy and just cut it off.
The handle is replaced as an assembly. Not saying you can't take it apart, but I never spent the time.I hope to get to the thumb switch,just not sure how to disassemble without breaking . Does the power run to the switch when the aux switch is on( green)? Anyone ever remove a thumb switch?
Okay.... I've looked all over this machine to no avail and don't know what else to do.....Would there be something in the valve body for the aux hydraulics sticking? I don't know where else to look.. The switch operates ok.. The function is just constant and should not be...That's why I think it's electrical.Any ideas would be greatly appreciated....The handle is replaced as an assembly. Not saying you can't take it apart, but I never spent the time.
Move the stems, see if the problem moves, if it does, it is a stem issue.Okay.... I've looked all over this machine to no avail and don't know what else to do.....Would there be something in the valve body for the aux hydraulics sticking? I don't know where else to look.. The switch operates ok.. The function is just constant and should not be...That's why I think it's electrical.Any ideas would be greatly appreciated....
What happens if you enable the aux hydraulics then try and slide teh coils off the stems. Do they feel like they are being pulled back down? This would indicate power is going to the coil when there shouldn't be. If not, it sounds like the stem is just sticking once it has been operated.
Bad right handle.Move the stems, see if the problem moves, if it does, it is a stem issue.
What happens if you enable the aux hydraulics then try and slide teh coils off the stems. Do they feel like they are being pulled back down? This would indicate power is going to the coil when there shouldn't be. If not, it sounds like the stem is just sticking once it has been operated.
