Understanding Dump Pumps: How They Work, Features & Applications

The dump pump from Parker Commercial Hydraulics is a workhorse for any dump truck or dump trailer application. In this article, we’ll explain how a dump pump works, the features that make this dump pump superior to its competition and explain applications that are meant for a dump pump.

How Does A Dump Pump Work?

Dump pumps are unique in the fact that they are essentially a gear pump and valve all in one. Each model of dump pump can be installed either as a 2 or 3 line. So, what does a 2- or 3-line installation mean?

Dump pumps for 2- and 3-line installation are the same. All dump pumps come with the components to plumb the system either way. The 3-line installation also allows for the use of a return line filter to help keep contamination out of the hydraulic system.

Dump Pump Features

The table below highlights the features of each series of dump pump:

Product Features	Description	Product Features	Description
G Series
Pump Type	Fixed	Theoretical Displacement	29 GPM @ 1800 RPM
Installation	2- or 3-line	Outlet Pressure	Up to 2500 psi
Speed	Up to 2400 rpm	Mountings	4-Bolt B / DIN / REMOTE
Shift Options	Mechanical or Air
SG Series
Pump Type	Fixed	Theoretical Displacement	38 GPM @ 1800 RPM
Installation	2- or 3-line	Outlet Pressure	Up to 2500 psi
Speed	Up to 2400 rpm	Mountings	4-Bolt B / DIN
Shift Options	Mechanical or Air
C Series
Pump Type	Fixed	Theoretical Displacement	48 GPM @ 1800 RPM
Installation	2- or 3-line	Outlet Pressure	Up to 2500 psi
Speed	Up to 2400 rpm	Mountings	4-Bolt B / REMOTE
Shift Options	Mechanical or Air

Dump Pump Installation

What is 2-line Installation?

A 2-line installation means that there will be 2 hydraulic lines hooked up to the pump. One inlet line that comes from the system reservoir and a line that goes to the hydraulic cylinder that raises the dump body. The picture on the left shows the dump pump valve spool in a neutral position. You’ll notice that oil enters the inlet of the pump, and the valve spool directs it back to the inlet of the pump. Essentially, the oil recirculates through the pump even when the dump body isn’t being raised.

When the spool is shifted to the raise position, the valve spool directs fluid out of the pump to the hydraulic cylinder that is raising the dump body.

When the spool is shifted to the lower position, oil from the hydraulic cylinder travels back into the pump, through the relief valve cartridge in the pump, and back to the system reservoir.

Two-line installations are for intermittent operation only. This is because in the neutral position, only a small amount of hydraulic oil is recirculating through the pump. If the pump is left in that position for too long, the oil and pump components will heat up to an extreme temperature that can cause catastrophic damage to the pump components.

What is 3-line Installation?

A 3-line installation means that there will be 3 hydraulic lines hooked up to the pump. One line is the inlet line that comes from the system reservoir. The second line goes to the hydraulic cylinder just like the 2-line installation. The third line is a return line that goes back to the system reservoir. There is also a sleeve that gets installed into the inlet port of the pump. This sleeve blocks oil from being able to recirculate in the pump. In the neutral position shown on the left, oil enters the inlet port, goes through the pump, and is directed back to the reservoir by the valve spool.

When the valve spool is shifted to the raise position, oil is allowed to flow out of the pump and into the hydraulic cylinder that is used to raise the dump body.

When the valve spool is shifted to the lower position, oil leaving the cylinder is directed back through the pump and out the return line back to the system reservoir.

Which Installation Method is Best For Me?

It is always best to choose the 3-line installation whenever possible for two main reasons:

Oil doesn’t recirculate through the pump in a neutral position. Oil is instead directed back to the system reservoir. This helps keep the oil and pump components from generating too much heat. Hot oil is allowed to mix with the cooler oil in the reservoir, keeping it at a good operating temperature.
You can install an oil filter in the return line from the pump to the system reservoir. Filtration is always a good idea when designing good hydraulic systems. Contamination is one of the leading causes of component failure.

Warnings for Using a Dump Pump System

A device to lock the control lever in a neutral position must be installed. Dump pump units without a lockable control lever may allow the dump bed to rise unintentionally while in transit. This can result in the loss of vehicle control, accidental injury, and/or property damage.
This can result in the loss of vehicle control, accidental injury, and/or property damage.
Failure to disengage the PTO from driving the dump pump when in transit may also allow the dump bed to rise unintentionally, leading to loss of vehicle control, accidental injury, and/or property damage.
You should also never work under a raised dump bed without first securely blocking the bed to prevent the dump bed from accidentally lowering.

Dump Pump Applications

Dump pumps are designed and manufactured specifically for applications that have a dump body. This could be a dump truck or a dump trailer. This line of dump pumps provides the right flow range for most applications that need 1800 rpms and 2000 psi of pressure. There are many different shaft sizes and mounting plates that will fit any PTO and also styles that will fit directly to the drive train of the vehicle.

Call your local Force America salesperson for more information and help select the correct pump for your application. They can also help you will get the correct return line filter setup for the 3-line installation. Contact one of our knowledgable salesperson at your local FORCE America Service Center or call 1-888-993-6723.