M1078 Air/Hydraulic Pump Electric Replacement

Hello all,

I'm looking at replacing the problematic pneumatic powered hydraulic pump on my M1078 with an electric powered hydraulic pump. There are reasonably priced pump/tank combos out there- It would seem a single port unit with gravity return would bolt right in, abandon the present air line and use the tethered control in conjunction with the present hydraulic manifold. The present system uses only 3 quarts of ATF but has space for a couple of gallons in the tank- must be room for excessive return under some condition. The pump I'm looking at is something like this, "Mophorn 12 Quart Single Acting Hydraulic Pump 12V Hydraulic Power Unit with Steel Reservoir for Dump Trailer Truck Car Lift Unit" Has anyone gone electric and if so what did you use for the new pump/tank? Thank you! [h=1][/h]

Don't know where y0u are getting gallons from...

From the -10 operators manual:

“Air/hydraulic power unit..................................................................................3 pt (1.4 L)”

The tank is in the pump. There is some fluid left in lines if you have a dry system you have to add more than the pump would normally hold. And yes an electric pump works just fine. You just need a button to activate it.

Hi Ronmar. I understand the capacity, was nothing that the oem has gallons of empty tank.

Hi Suprnan, any idea of the normal pressure or volume? The one I'm looking at is 1500 or 3200 psi and 3 gal per min. I figure use the 1500 port and it would be 3/4 gal in 15 seconds. Wonder how much fluid is in those pistons. Thanks for the help.

OD Green said:

Hi Ronmar. I understand the capacity, was nothing that the oem has gallons of empty tank.

Click to expand...

Sorry, you are loosing me... My AOP reservoir is 10” X 5” X 4” or 200 cu/in. If a part of it wasn't filled with pump, it could only hold 0.86 gallon total... All 4 cylinders hold .54 gal when fully extended.

When fully retracted the rod takes up 0.14 gal so the total volume for all 4 cylinders combined when retracted is 0.4 gal. Add in perhaps 0.1 gal for the 1/4” plumbing and it is still a tiny system...

Oh, that 0.14 gal displaced by the cylinder rods, thats your MAXIMUM working volume of the reservoir. with all 4 cylinders extended(highly unlikely) you would be sending 0.54 gal to the cylinders, but at the same time, the backside or rod end of the cylinders(double acting cylinders) would be returning 0.4 gal for a net change of 0.14 gal.

When performing a single function like lifting the cab, you send 0.19gal to the cylinder but at the same time it is returning 0.14 gal from the backside so the reservoir volume changes 0.05gal...

Thanks Ronmar! This is exactly what I needed-

For shiats and grins .... call Power Packer. Am assuming they are the company used for the new electrics on the present trucks since they made the ones we use. They might can give you some "generic specifications" as a guideline.

Hello coachgeo,

Thanks for the tip, I called and spoke with Fred in customer / tech support. Sent him photos and a flow schematic. He's checking to see if they have a suitable replacement. I think he said they made the hand pumps for these. One thing I did learn, these system are double acting-as noted by a gent on the FB FMTV page. There is power up, and power down. It gets confusing after that- does the pump reverse flow or does the hydraulic manifold invert the lines....

OD Green said:

Hello all,

I'm looking at replacing the problematic pneumatic powered hydraulic pump on my M1078 with an electric powered hydraulic pump. There are reasonably priced pump/tank combos out there- It would seem a single port unit with gravity return would bolt right in, abandon the present air line and use the tethered control in conjunction with the present hydraulic manifold. The present system uses only 3 quarts of ATF but has space for a couple of gallons in the tank- must be room for excessive return under some condition. The pump I'm looking at is something like this, "Mophorn 12 Quart Single Acting Hydraulic Pump 12V Hydraulic Power Unit with Steel Reservoir for Dump Trailer Truck Car Lift Unit" Has anyone gone electric and if so what did you use for the new pump/tank? Thank you! [h=1][/h]

Click to expand...

I was looking into doing something similar........


Below is what I have heard..... have not verified, but someone here probably will know the answer........

One thing I heard is that the cab tilt piston has flow safety check valves...... if you push fluid too fast, the valve will close and lock the piston in position. This is to prevent the cab from tilting way too fast. You would have to put in needle valves or some other flow limiter on both lines to the piston so that the cab cannot flip too fast.

Can someone verify this? Is there a write up?


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ramdough said:

... (have heard) One thing I heard is that the cab tilt piston has flow safety check valves...... if you push fluid too fast, the valve will close and lock the piston in position. This is to prevent the cab from tilting way too fast. You would have to put in needle valves or some other flow limiter on both lines to the piston so that the cab cannot flip too fast (or drop too fast).

Can someone verify this? Is there a write up? ...

Click to expand...

great idea IMHO..... just do it anyway.... adds safety.

The safety checks are shown on the schematic diagrams for the cab and tire crane cylinders. One of the things that help mitigate excessive flow are the small hoses, fittings and the valve block itself which has restricted orifices on crane and cab circuits.

I have heard of some replacing with 1-2 GPM pumps and it still functions. I believe the valve and plumbing are mitigating the excessive flow which keeps the cylinder from locking. I would like to hear what their cab tilt time is which would give a closer estimate how much actual max flow is getting thru the plumbing.

Since in hydraulics, the fluid must always flow, any flow that does not make it thru the plumbing to perform work, is forcing the pump to max pressure/load and pushing its way thru the safety relief on the pump and back to the reservoir.

The AOP takes around a minute... I would like around A 20 second cab tilt. With a .19 gal cab cylinder(probably closer to .18gal as the first inch of lift is unloaded) is between a 0.5 and 0.6 GPM flow rate.

A 2 GPM pump needs the wiring and contactor to provide the current for 2GPM of work at X pressure(relief pressure, because the fluid must flow). Anything more than the .5-.6(or less) the job requires is a waste. The restricted flow will also force too large a pump to always go to its peak pressure and always work at full load/current draw pushing excess fluid thru the safety.

An appropriately sized pump(.6 GPM) only needs 1/3 or so the energy and wiring of a 2GPM. It should also only ever work to enough pressure to perform the work, so it will rarely hit full load/relief pressure/electrical load...

I did some math a while back. The 34-2 manual says the cab minus windshield, rear windows and inst & fuse panels, steering column and steps/fenders weighs 1400 pounds. With those items installed I am estimating a complete stock cab weight around 1600#?

Based on the lift/balance point shown near the rear of the door window openings when changing out the cab(would be a little farther forward with the above items installed), and what part of the cab is over the pivot point when it balances at the top, I am estimating a center of gravity just below the bottom of the door window, above the front of the door handle.

Thats about 32” behind the pivot. The lift point is 13” behind the pivot. That means the weight at the lift point will be 2.67 times the cab weight. Or 3938# That divided by the surface area of the piston, 3.1416Sq/In means you need around 1253 PSI to lift the cab.

Of course the math is only as good as the numbers input. A +/- 2” CG difference at 1600# would put the required hydraulic pressure to lift between 1175-1332 PSI. That same 4” CG span at 1800# would require 1322-1498 PSI to lift.

Haven't had a chance to fit a gauge and confirm this, so FWIW...

Interested in moving to electric pump. Has anyone identified a pump and replaced it? How does it work?

Didn't Seth from Adventure Driven do this about a year or two back?

I seem to recall him posting about it when someone found a pump that worked. He said it was the one he had used.

I don't recall if it was posted here or on the LMTV FB group...

Pump number:Haldex Barnes 2200976 Hydraulic Pump T96929

this the info I have, from a SS member, sorry, dont know who it came from

Haldex Barnes 2200976 comes up with below 24v electric pump motor. some crossovers listed too!!

Unit Type Starter
Part Type UNIT
Voltage 24
Rotation CCW
Brief PUMP MOTOR

ISKRA DESCRIPTION AMJ4750
ISKRA OEM 11.216.206
JS BARNES 220-0976
LESTER 10793
PRESTOLITE MUF6102W
WESTERN MOTORS W-8963B


Hydraulic Pump T96929 comes up with nothing??

I have a Haldex Pump on mine. Just make sure you have adequate battery CCA's. My pump draws a lot of amps. I run the truck when using it. Some day I will do a write up. To lift the cab is around 1200 to 1500 psi.

I figured out an easy way to fit a pressure gauge today so I took some video which I will upload once I get it edited. I saw about 1400 on mine to lift the cab and about 2100 to lift the spare off the ground.

You need something that delivers about 0.5 GPM or less @1500 PSI for a 20-25 second cab tilt, If that much flow is even possible. My AOP tilts the cab to the balance point in about 56 seconds. So that is just under 0.2GPM at 1400PSI. I ran it to nearly 3000 PSI with a cylinder completely retracted to see what it is capable of, so the cab tilt and tire lift were absorbing 100% of the AOP’s output and only built to enough pressure to perform the work.

Reworked LMTV, how long does it take you to tilt your cab With the Haldex power unit? The small fittings and hoses along with the restricted orifices will limit flow to some level, so I am curious how much a pump with larger flow is actually able to force thru the system. Time to tilt with a known cylinder volume will give us a better idea what max flow is possible.

The issue with hydraulic power units and fixed valves is they work at 100% flow whenever they run. If the load cannot accept its full output flow, it builds pressure untill the relief opens to accept what flow the load cannot. The pressure built is directly reflected in the electrical load as pressure on the pump = motor torque increase = current draw increase. So a pump with a 2GPM flow and a 2500 PSI relief setting, is pushing what it can get thru the system at 2500 PSI, and the rest of the flow(probably several times more than what is going to the cylinder) is passing thru the relief.

Reworked LMTV, one thing you could do to possibly reduce your current draw would be to lower the relief valve setting as low as it can go and still lift the spare. Then you will only be pulling the current needed to reach that lower pressure...