M1078 Air/Hydraulic Pump Electric Replacement

[Third From Texas]

Someone (it most likely was on the FB LMTV page) was going to use an electric for the relocated tire lift on a camper build. They were asking about a motor they had selected, and it was the same one that Seth had used to replace his air-over-pneumatic cab pump and Seth highly recommended it.

Contact Seth at Adventure Driven (he's a member here as well).

 

[M1078MAN]

Someone (it most likely was on the FB LMTV page) was going to use an electric for the relocated tire lift on a camper build. They were asking about a motor they had selected, and it was the same one that Seth had used to replace his air-over-pneumatic cab pump and Seth highly recommended it.

Contact Seth at Adventure Driven (he's a member here as well).

Nope, not a FB user. I think it was Reworked, but for some reason I no longer have the message.

Ronmar-great video on pressures

 

[Reworked LMTV]

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...

The cab opens pretty fast. Ok, I will try the the relief setting idea. Thanks.

 

[hs10]

OUTSTANDING video, thank this is valuable information for everyone.

 

[Ronmar]

The cab opens pretty fast. Ok, I will try the the relief setting idea. Thanks.

Are you able to time how long it takes? how much flow your electric pump can actually push thru the system is a real important piece of info...

an even better data point would be to time a cab lift with your larger pump relief set to say 1500 PSI...

 

[ramdough]

I have heard that if you have too much flow, a safety valve will shut and lock the piston in place. May consider a needle valve on both sides to adjust flow rate.

But I am curious what someone that knows more than me comes up with.


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[Ronmar]

I have heard that if you have too much flow, a safety valve will shut and lock the piston in place. May consider a needle valve on both sides to adjust flow rate.

But I am curious what someone that knows more than me comes up with.


Sent from my iPhone using Tapatalk

There are restricted orifices in the control valve to keep the flow from exceeding the cylinder lockout limits. You should only need to add flow restriction if you changed the control valve...

 

[ramdough]

The guy that told me about the safety lockout removed the valve body and the pump only fed the cab tilt directly. He said he had to add the needle valves because without the valve body restriction, the piston would lock up.


Sent from my iPhone using Tapatalk

 

[Ronmar]

The guy that told me about the safety lockout removed the valve body and the pump only fed the cab tilt directly. He said he had to add the needle valves because without the valve body restriction, the piston would lock up.


Sent from my iPhone using Tapatalk

Yep, that would happen on a large pump without restriction.

 

[M1078MAN]

link to video on conversion

hope the original poster doesn't mind

 

[Coffey1]

Subscribed

 

[Ohiobenz]

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]

I picked up a hydraulic lift gate pump. It's 12vdc. The problem is using a single acting pump does not provide for a return, they traditionally activate single acting cylinders and bleed back through the pressure port.
When I get a chance I'm going to try to port the return into the vent port of the tank, and use a 3 way valve (center closed) for directing fluid to either lift or lower the cab.
The pump has a pressure control adjustment which allows to adjust the rate of lift. The pump will run and just bleed the excess back to the tank.

 

[coachgeo]

I picked up a hydraulic lift gate pump. It's 12vdc. The problem is using a single acting pump does not provide for a return, they traditionally activate single acting cylinders and bleed back through the pressure port.
When I get a chance I'm going to try to port the return into the vent port of the tank, and use a 3 way valve (center closed) for directing fluid to either lift or lower the cab.
The pump has a pressure control adjustment which allows to adjust the rate of lift. The pump will run and just bleed the excess back to the tank.

just get a dual acting pump..... one...... don't think you can even get the cab back down with a bleed back/gravity down pump... two it would be FREAKING DANGEROUS if you did....

 

[Ronmar]

I picked up a hydraulic lift gate pump. It's 12vdc. The problem is using a single acting pump does not provide for a return, they traditionally activate single acting cylinders and bleed back through the pressure port.
When I get a chance I'm going to try to port the return into the vent port of the tank, and use a 3 way valve (center closed) for directing fluid to either lift or lower the cab.
The pump has a pressure control adjustment which allows to adjust the rate of lift. The pump will run and just bleed the excess back to the tank.

Many single acting units actually have a return port, it is just capped/plugged. Got pics Or model number? the good thing about the single acting units is they have a check valve on their output. Whatever you put on there has to have a check valve on the output for the hand pump to continue to function.

Coachgeo, he was talking about adding the return line, So I am thinking he is using the existing valve? You are correct you need pressure to pull the cab back over the balance point, but the restricted orifice in the valve controls lowering speed under gravity. If it didn't, the cylinder would lock.

In my experience most lift gate units are way oversized to run the LMTV system. Yes you can lower the relief pressure which will lower the load somewhat, but the electrical load is still a factor of flow rate@ set pressure. You are still paying electrically for 100% of that work even though 90% of it is passing thru the relief back to the sump...

Oh, and if you are running one of these larger power packs, I would definitely NOT do so while the engine is running/alternator online. the high amperage load these large units require is really hard on the alternator.

 

[Reworked LMTV]

Many single acting units actually have a return port, it is just capped/plugged. Got pics Or model number? the good thing about the single acting units is they have a check valve on their output. Whatever you put on there has to have a check valve on the output for the hand pump to continue to function.

Coachgeo, he was talking about adding the return line, So I am thinking he is using the existing valve? You are correct you need pressure to pull the cab back over the balance point, but the restricted orifice in the valve controls lowering speed under gravity. If it didn't, the cylinder would lock.

In my experience most lift gate units are way oversized to run the LMTV system. Yes you can lower the relief pressure which will lower the load somewhat, but the electrical load is still a factor of flow rate@ set pressure. You are still paying electrically for 100% of that work even though 90% of it is passing thru the relief back to the sump...

Oh, and if you are running one of these larger power packs, I would definitely NOT do so while the engine is running/alternator online. the high amperage load these large units require is really hard on the alternator.

Yes and no. It depends on 2 things. A strong CCA rating and alternator output. With adequate batteries CCA you can run the vehicle. The alternator would only be taxed to the amperage that the batteries could not support. If the alternator is pushing more than it is rated, then sure, the alternator may be damaged if there is no limiting.

 

[Ronmar]

Yes and no. It depends on 2 things. A strong CCA rating and alternator output. With adequate batteries CCA you can run the vehicle. The alternator would only be taxed to the amperage that the batteries could not support. If the alternator is pushing more than it is rated, then sure, the alternator may be damaged if there is no limiting.

The voltage regulator doesn't know load or load sharing, it only knows output voltage. it will use full field excitation/full output to try and maintin that voltage. The batteries can supply current at reduced voltage, but the alt will bust itself trying to make rated voltage. When the voltage drops, because the alt is trying to be the higher voltage source, the alt will assume all load until it reaches its limit, then the batteries will carry the rest.

Here is a test for you, put a voltmeter on the batteries with the engine running. You should see 14.2ish on the 12v batts. Switching loads on and off that are within the alternators load limit, like All the lights and headlights, should show little or no change in voltage as the regulator can compensate for these loads. Now turn on your pump. If the voltage drops Significantly, you have just exceeded the output capacity of the alternator and it is running full bore trying to get back to 14.2v and fill the hole you have just made in the electrons.

Another issue you are fighting with this power system if you are pulling high 12V current is the 12V output from the alternator is a mix of field which is applied to 12 and 24 v windings simultaneously, and switched SCR/s which modulate the 12V output(basically a Switching power supply) because of this it doesn't like mismatched loads. It may even drop off line with large imbalances to help protect itself...

 

[Reworked LMTV]

My Haldex pump is 24 volt. I used heavy gauge wire to reduce losses. Voltage chosen to utilize all the batteries. Correct, a voltage drop will be noted with overloading. Low voltage heats the wires more and strains these motors.

 

[Ronmar]

My Haldex pump is 24 volt. I used heavy gauge wire to reduce losses. Voltage chosen to utilize all the batteries. Correct, a voltage drop will be noted with overloading. Low voltage heats the wires more and strains these motors.

24 is a better way to do this...

How long does it take to tilt your cab?

 

[Reworked LMTV]

24 is a better way to do this...

How long does it take to tilt your cab?

Not sure, but it's fast.

 

[Ohiobenz]