Cab and spare hydraulics problems M1078 LMTV

[Ronmar]

That sounds feasible. I'll try to extract those ball seats this weekend. I wonder how many times that cylinder has seized with the trucks in actual service.

IDK, but have sure come across it a lot on the forums. Mine locked up once. Was able to free it, like most people, by repeated up and down cycles. I think the real trick is after you pump up, which should release the safety check, you need to release the pressure very very slowly so it flows past the safety check and releases the stored pressure without triggering the safety. The condition and perhaps the design of the control valve may make that a challenge, so it immediately re-locks the safety when you shift the valve.

i was thinking if it happened again, I might try to pump it up and release the pressure by slowly cracking the hose fitting, but removed that whole crane before it happened again

 

[MatthewWBailey]

IDK, but have sure come across it a lot on the forums. Mine locked up once. Was able to free it, like most people, by repeated up and down cycles. I think the real trick is after you pump up, which should release the safety check, you need to release the pressure very very slowly so it flows past the safety check and releases the stored pressure without triggering the safety. The condition and perhaps the design of the control valve may make that a challenge, so it immediately re-locks the safety when you shift the valve.

i was thinking if it happened again, I might try to pump it up and release the pressure by slowly cracking the hose fitting, but removed that whole crane before it happened again

You removed the whole crane? So where's your spare now?

 

[Ronmar]

You removed the whole crane? So where's your spare now?

It is going to go on the back of the habitat box I have planned. I removed all that hardware for the tire crane, lifting arch and air filter/exp tank, so I could build the habitat right up close to the back of the cab so I can fit a pass-thru. The air-filter is going up on top of the cab. The expansion tank is down behind the bumper.

 

[MatthewWBailey]

It is going to go on the back of the habitat box I have planned. I removed all that hardware for the tire crane, lifting arch and air filter/exp tank, so I could build the habitat right up close to the back of the cab so I can fit a pass-thru. The air-filter is going up on top of the cab. The expansion tank is down behind the bumper.

IDK, but have sure come across it a lot on the forums. Mine locked up once. Was able to free it, like most people, by repeated up and down cycles. I think the real trick is after you pump up, which should release the safety check, you need to release the pressure very very slowly so it flows past the safety check and releases the stored pressure without triggering the safety. The condition and perhaps the design of the control valve may make that a challenge, so it immediately re-locks the safety when you shift the valve.

i was thinking if it happened again, I might try to pump it up and release the pressure by slowly cracking the hose fitting, but removed that whole crane before it happened again

It's been a few months but I wanted to circle back and show you my fix. I bought a 2.5" bore Magister tang cylinder with 1.5" rod. I installed the Prince flow control, as you suggested, on the rod end. Had to buy a "top link knuckle" since the off the shelf cylinders are rotated 90deg on axis vs the original cylinder and I need the ports to face upward. The knuckle took 3 months to arrive! However, oddly, with the knuckle and 16" stroke cylinder, the end-to-end measurement is exactly the same as the original cylinder when retracted. (Must be a conspiracy lol). The increased cylinder volume makes the lifting a little slower, but now there's no worries over those port check valves. Cylinder was $200 online. I had to put an extension hose on the rod end to get back to the original hydraulic lines. It's a bit beefier obviously.

 

[Ronmar]

Yea more volume, but the larger piston area will do the work at a lower pressure, so less strain on the AOP… Very nice!

 

[Awesomeness]

It's been a few months but I wanted to circle back and show you my fix. I bought a 2.5" bore Magister tang cylinder with 1.5" rod. I installed the Prince flow control, as you suggested, on the rod end. Had to buy a "top link knuckle" since the off the shelf cylinders are rotated 90deg on axis vs the original cylinder and I need the ports to face upward. The knuckle took 3 months to arrive! However, oddly, with the knuckle and 16" stroke cylinder, the end-to-end measurement is exactly the same as the original cylinder when retracted. (Must be a conspiracy lol). The increased cylinder volume makes the lifting a little slower, but now there's no worries over those port check valves. Cylinder was $200 online. I had to put an extension hose on the rod end to get back to the original hydraulic lines. It's a bit beefier obviously. View attachment 892878

Could you post the part numbers for all the things you used, so others could replicate the build?

 

[MatthewWBailey]

Could you post the part numbers for all the things you used, so others could replicate the build?

Sure thing see below. I made the 1" cross pin out of the old cylinder rod (I'm a hoarder) but those are generic. The CAT2 knuckle from QTP was hard to find but I found it at farmingparts.com.

the original pins work fine since the Magister cylinder has 1" holes. The knuckle needs that additional cross pin.

Overall it was a very off the shelf upgrade.

1/4" 2-Wire Hydraulic Hose x 18" with one #4 (1/4") FJIC and one #4 (1/4") MJIC fitting	Qty1
3/8 NPT 8 GPM Prince WFC-600 In-Line Flow Control 9-7960-6	Qty1
Hydraulic Cylinder Welded Double Acting 2.5" Bore 16" Stroke Tang WTG 2.5x16	Qty1
SAE 8 Male x 3/8" NPT Male 90 Degree Elbow 6806-08-06 Adapter 9-6806-8-6	Qty1
JIC 4 Male x 3/8" NPT Male Straight 2404-04-06 Adapter 9-2404-4-6	Qty1
SAE 8 Male x SAE 4 Female Straight 6410-08-04 Adapter 9-6410-8-4	Qty1
QTP Knuckle Hydraulic Top Link 25mm CAT2 #53467	Qty1
1" x 3-5/8" cross pin for Knuckle. Generic	Qty1
Total cost: (minus shipping)	$315

 

[MatthewWBailey]

Could you post the part numbers for all the things you used, so others could replicate the build?

Also here a picture of the knuckle and cylinder attachment at the top end, just for reference. I need a better pin clip but that's a trip to tractor supply.

 

[Awesomeness]

Thanks!

I had to put an extension hose on the rod end to get back to the original hydraulic lines.

That's the first hose listed in your Bill of Materials?

 

[MatthewWBailey]

Thanks!



That's the first hose listed in your Bill of Materials?

Yes. It's 5000psi hose from these guys...

 

[MatthewWBailey]

It's been a few months but I wanted to circle back and show you my fix. I bought a 2.5" bore Magister tang cylinder with 1.5" rod. I installed the Prince flow control, as you suggested, on the rod end. Had to buy a "top link knuckle" since the off the shelf cylinders are rotated 90deg on axis vs the original cylinder and I need the ports to face upward. The knuckle took 3 months to arrive! However, oddly, with the knuckle and 16" stroke cylinder, the end-to-end measurement is exactly the same as the original cylinder when retracted. (Must be a conspiracy lol). The increased cylinder volume makes the lifting a little slower, but now there's no worries over those port check valves. Cylinder was $200 online. I had to put an extension hose on the rod end to get back to the original hydraulic lines. It's a bit beefier obviously. View attachment 892878

Correction: after a few lifts, it seems the retracted length is 1/2" longer than the original cylinder. I was wrong about the length. The extended length was identical not the retracted.. See pic of crane angle. I used a 3" longer chain so the tire would still sit in the cradle. It's not quite perfect yet but I think I can modify the rod end hole position to make up the difference.

 

[MatthewWBailey]

Correction: after a few lifts, it seems the retracted length is 1/2" longer than the original cylinder. I was wrong about the length. The extended length was identical not the retracted.. See pic of crane angle. I used a 3" longer chain so the tire would still sit in the cradle. It's not quite perfect yet but I think I can modify the rod end hole position to make up the difference.

Just a final update. Finally finished the rod end hole position mod. I took out 1" of material on either side and then just rewelded it. The tire goes all the way up and into the cradle now.