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Monarch 12v hydraulic power pack ?

dave_dj1

dave_dj1

Red Skull Member
Joined
May 23, 2020
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1290
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Jackson NY
I have a Monarch 12v hydraulic power pack on my F250 that is virtually new, it is power up, gravity down. It comes down sooo slooow. My question is is there an adjustment on it to allow it to come down quicker? I understand I don't want it to come crashing down but damn. I run ATF in it, the cylinder is about a 5" bore by 24" stroke. I have the other end hooked into the reservoir so that on extension the fluid is pushed out and back into the reservoir and then when it's lowered it gets sucked back into the other end as the fluid comes out of the bottom end. I'm including a pic to try an explain it.
5HxdcAyh.jpg
 
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Probably a fixed size orfice on the return side of the cylinder. That way it doesn't crash down if a line blows. Scissor lifts are set up this way.
 
Jwredneck said:
Probably a fixed size orfice on the return side of the cylinder. That way it doesn't crash down if a line blows. Scissor lifts are set up this way.
Click to expand...

I'm thinking maybe limiting orifice is in the pump.
ETA: when I got this dump bed it had a pto pump was plumbed the same way I have it.
 
It's cold out so it will come down slow. Probably be fine come summer. You could change or remove the restriction fitting and install an adjustable one. I used these on my boom lift project. Surplus center has them in many sizes. The go from closed to full open by turning an adjuster dial.

Also check the pivot pins. I've known a few with seized pins that would get stuck up.
 
Dethmachinefab said:
It's cold out so it will come down slow. Probably be fine come summer. You could change or remove the restriction fitting and install an adjustable one. I used these on my boom lift project. Surplus center has them in many sizes. The go from closed to full open by turning an adjuster dial.

Also check the pivot pins. I've known a few with seized pins that would get stuck up.
Click to expand...

Pins are freshly installed and greased. I'll look into the adjustable valves. Thanks
 
sell it and get one with power up and down.

seems like used units go for more than new from amazon. iirc the last one i bought was 200ish. also, i've done a fair amount of dump bodies and the power down is nice to have to suck the bed down tight. power down comes in handy in alot of situations. without power down i would install latches to secure the bed when down.
 
No easy fix. If you open the orfice up it's going to be too fast when it's summer and the oil is warm or if there's a load. Also, with the geometry, the closer it gets to fully down the faster it's going to be dropping.

Also, the geometry of the ram is piss poor - when the bed is down the ram is pretty much parallel to the bed, which means when you need the most force to lift the bed the ram has the least useful force, and with any real load you're almost certainly going to be bending stuff instead of dumping. 5" ram @ 2000 psi makes about 20 tons of force.... If the lower pivot of the cylinder was dropped down a bit it would be a much better design.
 
sdmuleman said:
No easy fix. If you open the orfice up it's going to be too fast when it's summer and the oil is warm or if there's a load. Also, with the geometry, the closer it gets to fully down the faster it's going to be dropping.

Also, the geometry of the ram is piss poor - when the bed is down the ram is pretty much parallel to the bed, which means when you need the most force to lift the bed the ram has the least useful force, and with any real load you're almost certainly going to be bending stuff instead of dumping. 5" ram @ 2000 psi makes about 20 tons of force.... If the lower pivot of the cylinder was dropped down a bit it would be a much better design.
Click to expand...

I appreciate your input. I understand the geometric short comings, not much I can do about it. It's a factory dump bed that is old, I have the same set up on my dump trailer. I think on the first dump trailer I built I had around 13* for the ram, 4" ram and it did grunt a bit to get started. I'm not looking to haul 5 yards of gravel, just some junk and firewood. I'm hoping that the extra foot I added to the bed will help with lift, the cantilever effect.
 
tracyb said:
sell it and get one with power up and down.

seems like used units go for more than new from amazon. iirc the last one i bought was 200ish. also, i've done a fair amount of dump bodies and the power down is nice to have to suck the bed down tight. power down comes in handy in alot of situations. without power down i would install latches to secure the bed when down.
Click to expand...

I am seriously considering getting a new power pack with power down.
 
My dump truck has a 3 stage ram and no matter what stage it's slow in the winter and it's WAY heaver built than yours. The PO put the pump and tank in the truck so the heat from the cab would warm the fluid. Could you put some weight on the bed for the cold weather to help?
 
MattS said:
My dump truck has a 3 stage ram and no matter what stage it's slow in the winter and it's WAY heaver built than yours. The PO put the pump and tank in the truck so the heat from the cab would warm the fluid. Could you put some weight on the bed for the cold weather to help?
Click to expand...

I honestly don't think that is the problem, I think it's the fact that a 5" plunger is trying to push fluid through a 1/4" hose and then the orifice in the pump and back into the tank. I would think ATF isn't going to be too thick ever.
I'm looking at new D/A units on egay right now. Most of them have SAE -6 ports, that will give me a large increase in flow.
.250 hole = 0.065449846949787 inches[SUP]3 volume
.333 hole = [/SUP]0.15747913854527 inches[SUP]3[/SUP]
 
dave_dj1 said:
I am seriously considering getting a new power pack with power down.
Click to expand...

if the rod gland is set up for pressure, just put a new valve on it and you'll have power down

seal in there might be kinda shitty though if it is just set up to do that fluid volume compensating trick and never intended to have pressure in there
 
dave_dj1 said:
I have a Monarch 12v hydraulic power pack on my F250 that is virtually new, it is power up, gravity down. It comes down sooo slooow. My question is is there an adjustment on it to allow it to come down quicker? I understand I don't want it to come crashing down but damn. I run ATF in it, the cylinder is about a 5" bore by 24" stroke. I have the other end hooked into the reservoir so that on extension the fluid is pushed out and back into the reservoir and then when it's lowered it gets sucked back into the other end as the fluid comes out of the bottom end. I'm including a pic to try an explain it.
Click to expand...

Can you give us a model number on the package assembly?

You could have asked i have a engine how do i go fast and it would feel the same

How slow are we talking?

Usually the relief valve and the return restriction are the same thing. On the last monarch i worked on we had rebuild the motor and the valve assembly and it was a allen key and a jam nut.

So there is a possibility that by adjusting this you could either have a overpressure situation or not enough pressure to do normal operation. With a model number we can find the schematic and help more
 
A_G said:
Can you give us a model number on the package assembly?

You could have asked i have a engine how do i go fast and it would feel the same

How slow are we talking?

Usually the relief valve and the return restriction are the same thing. On the last monarch i worked on we had rebuild the motor and the valve assembly and it was a allen key and a jam nut.

So there is a possibility that by adjusting this you could either have a overpressure situation or not enough pressure to do normal operation. With a model number we can find the schematic and help more
Click to expand...

The tag is pretty much worthless, mostly rubbed off. I'll see if I can find some defining markings on it tomorrow. Thanks
 
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