12K Hydraulic Trailer Jack Kit – Single Double Dump & Jack Combo
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We offer the following methods of delivery:
- Same day Freight Shipping when ordered Mon-Fri before 12pm central time. (excluding holidays)
- Pickup from our Mandeville, Louisiana warehouse
- In some cases, free shipping - please contact us: sales@primarymover.com or call 985-888-6554
One power unit for your gravity-down dump bed and 12K hydraulic jack
The Primary Mover 12K Hydraulic Trailer Jack Kit with Single Double Power Unit operates a compatible single-acting dump cylinder and double-acting hydraulic jack from one hydraulic power unit. Your dump bed retains powered raising and gravity lowering, while the jack receives powered extension and retraction.
The kit combines one 12,000 lb jack leg with a 12V Single Double power unit, six-gallon steel reservoir and 15-foot four-button pendant. Choose bolt-on or weld-on jack mounting.
Power unit, reservoir, pendant and Group 31 battery tray included. Battery not included. The dump cylinder and dump-body hardware are separate.
- One 12K hydraulic jack leg with a 20-inch hydraulic stroke.
- Single-acting dump circuit: powered raise and gravity lower through an SAE-8 work port.
- Double-acting jack circuit: powered extension and retraction through two SAE-6 work ports.
- Separate listed relief settings: approximately 2,800 PSI for the dump circuit and 3,200 PSI for the jack circuit.
- Six-gallon steel hydraulic reservoir.
- 20-foot, four-button wired pendant for dump and jack control.
- Dual counterbalance valves on the jack cylinder.
- Two 72-inch jack hoses; a two-hose, 120-inch upgrade is available at additional cost.
- Group 31 battery tray included.
- Bolt-on or weld-on mounting choices.
- 12-month limited jack warranty, subject to warranty terms.
What Single Double means
Single Double describes the two different circuit types built into the power unit. The single-acting circuit supplies pressure to raise the dump cylinder, then opens a return path so the dump body can lower by gravity. The double-acting circuit sends pressure to either side of the jack cylinder for powered movement in both directions.
This arrangement lets you add powered jack operation while retaining a compatible power-up/gravity-down dump cylinder. It supplies a replacement or new power unit that serves both functions.
A Dual Double kit serves two double-acting circuits. Choose the circuit arrangement that matches your dump cylinder and the way it is intended to lower.
Separate dump and jack circuits
Single-acting dump circuit
The dump circuit uses an SAE-8 work port. Its listed relief setting is approximately 2,800 PSI. It powers the dump cylinder for raising and provides a return path for gravity lowering.
Double-acting jack circuit
Two SAE-6 work ports supply the jack. The jack circuit’s listed relief setting is approximately 3,200 PSI, with powered extension and retraction.
The jack circuit’s pressure setting does not increase the pressure available to the dump circuit. Check that your dump cylinder or hoist can lift the intended load at the dump circuit’s specified operating conditions.
15-foot four-button pendant
The included wired pendant controls both functions:
- UP: powers the dump cylinder to raise the body.
- DOWN: opens the dump return circuit for gravity lowering.
- IN / OUT: power the jack in its two movement directions.
The jack’s extension and retraction commands depend on the installed hose routing. Identify the actual directions and check the controls during installation before operating under load.
Six-gallon steel reservoir and telescopic-cylinder compatibility
The supplied power unit has a six-gallon steel reservoir. A single-acting telescopic dump cylinder can be a suitable application when its oil-volume, pressure and flow requirements match the complete system.
Reservoir selection depends on the cylinder’s required oil volume through its intended stroke and the reservoir’s usable capacity. Nominal tank size does not mean every gallon is available to the cylinder; the installation needs suitable oil supply, return space and operating clearance.
For a 12K 144-inch telescopic cylinder or another large-volume application, contact us to confirm reservoir sizing before ordering. Send the cylinder model or required oil capacity, stroke and intended application.
Motor size, delivered flow at working pressure and electrical supply also affect hydraulic performance. Read how power-unit size, pressure and flow affect trailer-jack operation .
Dual counterbalance valves and premium jack construction
The jack uses dual counterbalance valves for load-control functions on both sides of its cylinder. They help resist unintended retraction while supporting the trailer and unintended extension while the leg is stowed.
During lowering, the valves control outgoing oil to help manage load-driven movement. The complete hydraulic circuit, valve settings and load determine actual operating behavior.
- Painted 4-inch-square steel outer tube.
- Stainless steel cap.
- Galvanized inner sleeve.
- Hot-dip galvanized foot.
- Rigid hydraulic piping on the jack cylinder.
- Grade 8 hardware for applicable mounting connections.
Learn why dual counterbalance valves matter on hydraulic trailer jacks .
What the Single Double jack kit includes
- One Primary Mover 12K hydraulic jack assembly with a 20-inch stroke, dual counterbalance valves and your selected bolt-on or weld-on configuration
- One Primary Mover 12V Single Double hydraulic power unit with a six-gallon steel reservoir
- One 20-foot, four-button wired pendant
- Two 72-inch hydraulic jack hoses with JIC-6 straight and 90-degree end fittings
- Hydraulic connection fittings for the listed jack hookup
- Two 4-gauge battery cables
- One Group 31 battery tray
- Installation hardware supplied with the selected jack configuration
Optional hose upgrade: two 120-inch jack hoses are available at additional cost.
Not included: battery, dump cylinder, dump-body hardware or optional transition adapters. Confirm any additional dump-circuit hoses, fittings and installation components needed for your trailer.
Single Double jack kit specifications
| Jack lifting rating | 12,000 lb |
|---|---|
| Jack assemblies included | One |
| Jack stroke | 20 inches |
| Included power unit | Primary Mover 12V Single Double |
| Reservoir | Six-gallon steel tank |
| Dump operation | Single acting: powered raise / gravity lower |
| Dump work port | SAE-8 |
| Listed dump relief setting | Approximately 2,800 PSI |
| Jack operation | Double acting: powered extension / retraction |
| Jack work ports | Two SAE-6 ports |
| Listed jack relief setting | Approximately 3,200 PSI |
| Remote | 20-foot wired, four-button pendant |
| Jack load-control valves | Dual counterbalance valves |
| Standard jack hoses | Two 72-inch hoses, JIC-6 straight and 90-degree ends |
| Optional hose upgrade | Two 120-inch jack hoses, additional cost |
| Mounting choices | Bolt-on or weld-on |
| Battery tray | Group 31 tray included |
| Battery included | No |
| Recommended fluid | Non-synthetic ATF, following product instructions |
Mounting and system compatibility
Compare the jack’s mounting pattern, complete retracted and extended dimensions, above-frame projection and stowed ground clearance with your trailer. Bolt-on mounting needs a compatible pattern and suitable structural support. Weld-on mounting needs appropriate support and welding for the intended load.
Compatible bolt-on transition plates may provide additional mounting options. These adapters are sold separately.
The jack’s 12,000 lb lifting rating does not establish dump-body lifting capacity or increase trailer GVWR, frame capacity or other component ratings. Match both hydraulic functions to the intended load and installation.
Keeping your existing single-acting power unit?
This kit supplies a new Single Double power unit. If you intend to retain a compatible existing single-acting power unit, compare the jack-only listing with the appropriate X-Block hookup kit .
Read how an X-Block operates a double-acting jack from a single-acting power unit , or use the Jack Kit Selector to compare configurations.
Single Double dump-and-jack questions
Does this kit retain gravity-down dump operation?
Yes. Its single-acting dump circuit powers the cylinder to raise the body and opens a return path for gravity lowering. The separate jack circuit powers extension and retraction.
How is this different from the Dual Double kit?
Single Double combines one single-acting dump circuit and one double-acting jack circuit. Dual Double provides two double-acting circuits. Choose the system that matches your dump cylinder and intended operation.
Will the six-gallon reservoir work with my telescopic cylinder?
Confirm the cylinder’s required oil volume, stroke, pressure and flow against the complete installation and the reservoir’s usable capacity. Contact us before ordering for a 12K 144-inch cylinder or another large-volume application.
Do the dump and jack circuits have the same relief setting?
No. The listed settings are approximately 2,800 PSI for the single-acting dump circuit and 3,200 PSI for the double-acting jack circuit. The higher jack-circuit setting does not apply to the dump cylinder.
Do I need an X-Block with the supplied power unit?
No. The included Single Double power unit already provides the single-acting dump and double-acting jack functions. An X-Block is an alternative when retaining a compatible existing single-acting power unit.
Does the package include a battery or dump cylinder?
No. A Group 31 battery tray is included, but the battery is separate. The dump cylinder, dump-body hardware and any additional dump-circuit plumbing are also separate.
Can I order longer jack hoses?
Yes. Two 72-inch hoses are standard; two 120-inch hoses are available as an upgrade at additional cost. Confirm the routing and required length before ordering.
Manuals, warranty and demonstration
- Download the Primary Mover 12K Hydraulic Trailer Jack Manual
- Browse power-unit installation manuals and product documentation
- View warranty coverage and terms
- Learn about dual counterbalance valves
Need help matching your cylinder and jack? Call 985-888-6554 or email sales@primarymover.com with your dump-cylinder model, required oil capacity and jack mounting dimensions. You can also compare hydraulic trailer jacks and kits .