12v hydraulic power pack questions

[davedj1]

I built a dump trailer this past summer and used a used hydraulic unit from an old liftgate. Well it took a crap yesterday.
I am going to order a new unit but was wondering what the consensus is on single acting vs double acting? I have a 4 x 24 double acting cylinder on the dump trailer, i never used it as a double acting. I had it power up and gravity down. The hydro unit I had was a da but I capped the return port and it worked ok, very slow going down but worked. Now that I have to replace it I'm not sure if I should buy a da or sa unit.
Sorry for the long winded post but hate to spend hard earned cash on the wrong parts.
thanks,
dave

 

[oldnslo]

I built a dump trailer this past summer and used a used hydraulic unit from an old liftgate. Well it took a crap yesterday.
I am going to order a new unit but was wondering what the consensus is on single acting vs double acting? I have a 4 x 24 double acting cylinder on the dump trailer, i never used it as a double acting. I had it power up and gravity down. The hydro unit I had was a da but I capped the return port and it worked ok, very slow going down but worked. Now that I have to replace it I'm not sure if I should buy a da or sa unit.
Sorry for the long winded post but hate to spend hard earned cash on the wrong parts.
thanks,
dave

Would you ever have a use for the power down feature? If yes you should consider that now. If no why add the extra run time to your DC motor since with a SA system the motor should not run when lowering via gravity.

Roy

 

[Wayne County Hose]

For me it would depend on the price difference. However, if you buy a double acting power unit plumb it as such. Reason being, your cylinder will last a lot longer with fluid on both sides of the piston seals. I have had loads of these cylinders brought to me for repair. The rod end has a breather which of course lets moisture in. This moisture ruins the internals of the cylinder. If you keep it as a single acting cylinder, clean the breather regularly and squirt some tranny fluid into the rod end periodically. For my customers with this setup I always recommended plumbing the rod end into a 3/8" fuel filter. They filter out contaminants infinitely better than the plug style breather.

 

[davedj1]

Thanks guys!
I don't think I will ever "need" power down, it might be faster in the winter but I don't use it much in winter. Cost wise, of course the DA costs more but not all that much.
Wayne, thanks for the info, good to know. What do you think about plumbing the vent into the box that holds the hydro unit?
Here is a pic of the box, it's plastic and large.

 

[muddstopper]

For me it would depend on the price difference. However, if you buy a double acting power unit plumb it as such. Reason being, your cylinder will last a lot longer with fluid on both sides of the piston seals. I have had loads of these cylinders brought to me for repair. The rod end has a breather which of course lets moisture in. This moisture ruins the internals of the cylinder. If you keep it as a single acting cylinder, clean the breather regularly and squirt some tranny fluid into the rod end periodically. For my customers with this setup I always recommended plumbing the rod end into a 3/8" fuel filter. They filter out contaminants infinitely better than the plug style breather.

I built a dump trailer a few years ago and used a double acting cylinder but only had gravity down. instead of venting one end of cylinder I went ahead and hooked it up to the control valve. The control valve was electric over hydraulic but whenever I hit lower, only the valve switched and pump didnot turn on. I feel this allowed the cylinder to gravity drop while vacume sucking some oil into the rod end of cylinder thru the open valve. Cylinder closed to atmosphere and lubricated to boot.

 

[Doppelgangar]

there is not much that goes wrong with these pump units.

Brushes were in the motor and the Vain pump were the vains.

Before going too far you might just want to check those items first.

the solonoid some time stick and get away with just a good clean.

Most are installed on trucks and get no maintance except for when the oil gets low.

 

[davedj1]

Dopplegangar, I checked the solenoid and it's fine, pulled the motor apart and the brushes on the hot side are very low but look to be ok. The motor turns freely by hand, I don't dare hook it to electric as once it's removed there is no end on one end. I have a small slotted adapter from the motor to the pump shaft and I could turn the pump in one direction fine but turning it clockwise it felt like it was binding , almost like you were winding a rubber band. I know what you mean about no maintenance, I got this one off a liftgate and it was a wreck! The tank had no bottom (it had rotted off). I cut all the rust off and welded a new bottom on the tank. I figure by the time I buy a motor, it's just as easy to buy the whole thing. I took the pump apart to check the two gears and found nothing binding in there. I have some time today I may actually give here a once over and see if I can get her going. The motor looks like a ford starter motor.
thanks for the input.
dave

 

[davedj1]

Ok, tore it into it today and found that the motor is shot. I called around to find another motor and the price was half as much as I can buy a whole new unit for.

The reservoir was rotted out when I bought it so I patched it up but I think there is still a small leak. To buy the motor and new reservoir, I may as well buy the whole thing.

 

[davedj1]

Well, here's an update. I was given the name of a shop today that rebuilds motors, not too far away so I called them and they said one day turn around time. I drove out there this afternoon and dropped it off, for $50 they will rebuild the motor, new brushes etc. I asked about a new motor and they said sure, for $115 so I bought the new motor and am having them rebuild the old one. I have it all back in and running, this time with atf.