Single or double acting dump trailer pump?

James Eric · Jan 7, 2020

I am just starting to bring an old dump trailer back to life. It has a double acting cylinder with a single acting pump. As you can see in the picture, the top port on the cylinder has rubber hose that returns to the tank. Since I am installing a new dump pump kit, should I switch to a double acting pump or continue the current single acting setup?

6x12 dump trailer
Cross 3 inch bore , 24 inch stroke double acting cylinder
(2) 3500 pound axles
Factory built, unknown manufacturer

PILOON · Jan 7, 2020

You only need the hydraulic power to raise the dumper, gravity brings it back down.
The builder simply used the cylinder he had on hand and rendered it to single action mode.

4570Man · Jan 7, 2020

If it worked before why bother changing it?

Ron of Va · Jan 7, 2020

I have a double action hydraulic cylinder on my dump trailer.

Pros; I needed to transport an 800 lb. safe but couldn't get it into the back. I raised the dump trailer into the vertical position. Strapped up the safe against the back of the trailer and lowered the bed. The double action cylinder pulled the safe up off the ground to where we could slide it into the bed.

Cons; I dumped a load of debris at the city dump. The hydraulic pump refused to operate to lower the bed. It did not have a relief valve. I couldn't drive home with the bed up, so after a couple of hours of work and a new battery. I got it working again. I later installed an emergency relief valve system, to drain the fluid out of the cylinder and into the reservoir to lower the bed in an emergency. That cost about $125. Double action puts more strain on the battery.

davedj1 · Jan 7, 2020

I have power up, gravity down and run transmission fluid in the pump, never had an issue no matter how cold it gets.

davedj1 · Jan 7, 2020

I have power up, gravity down and run transmission fluid in the pump, never had an issue no matter how cold it gets.
I too have a double acting cylinder and ran a hose back to the tank just to have some fluid on reserve.

3 Horse Ranch · Jan 7, 2020

I operated dump trucks and trailers for 14 years and none were equipped with a double acting cylinder. If its good enough for the industry, it should be good enough for anybody. The only time I operated a vehicle with a double acting cylinder was in and old Ford 9000 flatbed lumber delivery truck, it only came in handy when delivering to city lots with overhead wires where it was necessary to power down to clear the wires before pulling out from under the load.

4570Man · Jan 7, 2020

My ton dump truck is a double acting cylinder. I can’t think of any advantage to having power down on a dump truck. The only advantage I can think of is it doesn’t require as big of an oil tank. The downside is it’s a lot slower to go down.

Thunder chicken · Jan 14, 2020

Ron,
I’m curious how you plumbed in your ‘emergency’ lower?
I too have a double acting dump trailer. When I use it on the tractor with tractor hydraulics it works great! When I use it on the truck with the pump.....I’ve been stranded before too. I’ve even added a 4ga wire and associated solenoids, breakers and fuses to have about 40 amps of power trying to keep the battery charged. My fully charged battery (deep cycle group 24) lasts one dump. I’m thinking the pump motor is getting tired and must be drawing a heck of a current tire drain the batteries so fast, which over a few months seems to destroy them.
OP, go single acting!!!!

Ron of Va said:
I have a double action hydraulic cylinder on my dump trailer.

Pros; I needed to transport an 800 lb. safe but couldn't get it into the back. I raised the dump trailer into the vertical position. Strapped up the safe against the back of the trailer and lowered the bed. The double action cylinder pulled the safe up off the ground to where we could slide it into the bed.

Cons; I dumped a load of debris at the city dump. The hydraulic pump refused to operate to lower the bed. It did not have a relief valve. I couldn't drive home with the bed up, so after a couple of hours of work and a new battery. I got it working again. I later installed an emergency relief valve system, to drain the fluid out of the cylinder and into the reservoir to lower the bed in an emergency. That cost about $125. Double action puts more strain on the battery.