12K Hydraulic Trailer Jack – Bolt-On or Weld-On with Dual Counterbalance Valves
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12K hydraulic trailer jack with dual counterbalance valves
The Primary Mover 12K Hydraulic Trailer Jack combines a 12,000 lb lifting capacity, 20-inch hydraulic stroke and dual counterbalance valves in your choice of bolt-on or weld-on configuration. Designed for compatible dump trailers and other trailer applications, it provides powered extension and retraction when connected to a suitable hydraulic system.
Premium construction includes a stainless steel cap, hot-dip galvanized foot, galvanized inner sleeve and rigid hydraulic piping on the cylinder. Dual counterbalance valves help control load-driven movement and maintain the leg’s intended position, whether extended or retracted.
This listing is for one hydraulic jack assembly only. A hydraulic power unit, remote control, connection hoses, fittings and X-Block kit are not included.
- 12,000 lb rated lifting capacity.
- 20-inch hydraulic stroke.
- Double-acting cylinder: powered extension and retraction with a compatible hydraulic circuit.
- Dual counterbalance valves: load control on both sides of the cylinder.
- Mounting options: bolt-on or weld-on.
- Painted 4-inch-square outer jack tube.
- Stainless steel cap.
- Hot-dip galvanized foot and galvanized inner sleeve.
- Rigid hydraulic piping on the cylinder.
- 12-month limited warranty, subject to warranty terms.
Hold the jack extended and keep it retracted
A trailer jack needs to control its load as well as lift it. When the leg is supporting the trailer, it should remain extended. When the leg is stowed for travel, it should remain retracted.
The jack’s dual counterbalance valves provide load-control functions for both sides of the hydraulic cylinder. They help resist unintended retraction under load and unintended extension when the jack is retracted.
During lowering, the trailer’s weight can try to drive the cylinder faster than the pump supplies oil. Counterbalance valves control outgoing oil flow to help reduce runaway movement and support smoother, more controlled operation. Actual movement depends on the complete hydraulic system and load.
More than a basic check valve
A check valve blocks reverse flow. A pilot-operated check valve can release that flow when pilot pressure is applied, but it is primarily an on/off load-holding device. A counterbalance valve also modulates outgoing flow to control an overrunning load.
When comparing hydraulic jacks, check both the valve type and whether the arrangement protects both cylinder sides. A general “load-holding valve” description does not establish those details.
Read why dual counterbalance valves matter on hydraulic trailer jacks .
Premium construction for trailer service
- Stainless steel cap: a corrosion-resistant component at the top of the jack.
- Hot-dip galvanized foot: corrosion protection for the component that contacts the ground.
- Galvanized inner sleeve: protection for the exposed moving section of the jack.
- Rigid cylinder piping: the cylinder uses hard piping rather than a flexible hose running along its side. External hydraulic connection hoses are still required.
- Painted steel outer tube: a 4-inch-square jack structure for the intended application.
20-inch stroke with a practical mounting layout
More stroke is not automatically a better fit. The useful lifting range depends on the jack’s mounting height, retracted dimensions, required ground clearance and trailer coupling height.
The Primary Mover jack provides 20 inches of hydraulic travel. On suitable bumper-pull installations, mounting it with below-frame clearance similar to the original jack can provide useful lifting reach without unnecessary projection above the trailer frame.
Compare the mounting drawings with your actual trailer and tow vehicle. Applications requiring additional reach, including some gooseneck installations, should be evaluated individually.
Choose bolt-on or weld-on mounting
Bolt-on hydraulic jack
Choose the bolt-on version when its mounting pattern and dimensions match your trailer or a suitable adapter. Confirm mounting-hole spacing, frame clearance and structural support before ordering.
Our bolt-on transition plate provides another mounting option for compatible configurations. Transition plates and adapters are sold separately.
Weld-on hydraulic jack
Choose the weld-on version for a suitable welded installation. The trailer structure, mounting arrangement and welding must provide the support required for the application.
Need a different mounting arrangement? Contact us with photos and dimensions of your existing jack mount. We can help identify an appropriate jack configuration or transition bracket.
Using an existing hydraulic power unit?
Existing double-acting system
A compatible double-acting hydraulic circuit can supply pressure to either side of this jack for extension and retraction. Supply the appropriate hoses, fittings and controls, and match the power unit’s pressure and flow to the jack’s requirements.
If the same power unit also operates your dump body, the system needs an appropriate circuit-selection arrangement. Review the applicable add-on kits or contact us for help matching the components to your existing setup.
Existing single-acting, power-up/gravity-down system
Buy this jack, then add the X-Block Poly Tank or Steel Tank Kit. The X-Block allows a compatible existing single-acting power unit to power both extension and retraction of the double-acting jack.
The complete X-Block kit includes the adapter, three-port SAE-8 ORB manual selector ball valve, connection and return hoses, two 72-inch jack hoses, jack fittings and the selected tank-return fitting. For a compatible installation, it supplies the hydraulic components needed to connect this jack to your existing single-acting setup.
Both kit versions contain the same components except for the tank-return fitting:
- Poly Tank Kit: 3/4-inch NPT to 3/8-inch JIC tank-return fitting.
- Steel Tank Kit: 1/4-inch NPT to 3/8-inch JIC tank-return fitting.
Confirm your actual return-port size and that the included hoses reach the jack. Some power units also have a suitable return port that routes oil back to the reservoir.
Add the complete X-Block Poly or Steel Tank Kit .
In this arrangement, the manual selector valve chooses the dump or jack circuit. The red X-Block valve chooses jack extension or retraction. Use the power unit’s UP button for both jack movements, stopping the pump before changing valve positions.
What this listing includes
- One Primary Mover 12K hydraulic trailer jack assembly
- Integrated double-acting hydraulic cylinder with 20-inch stroke
- Dual counterbalance valves
- Selected bolt-on or weld-on configuration
- Jack foot and associated jack assembly components
Not included: hydraulic power unit, remote control, external hydraulic hoses, connection fittings, X-Block kit, battery or optional transition adapters.
12K hydraulic trailer jack specifications
| Rated lifting capacity | 12,000 lb |
|---|---|
| Hydraulic stroke | 20 inches |
| Cylinder operation | Double acting |
| Load-control valves | Dual counterbalance valves |
| Outer jack tube | 4-inch square, painted steel |
| Mounting options | Bolt-on or weld-on |
| Top cap | Stainless steel |
| Inner sleeve | Galvanized |
| Foot finish | Hot-dip galvanized |
| Cylinder piping | Rigid hydraulic piping |
| Power unit included | No |
| Warranty | 12-month limited warranty, subject to warranty terms |
The jack’s lifting rating does not increase your trailer’s GVWR, frame capacity or other component ratings. Use the jack within its rated capacity and stroke, with suitable mounting support and a compatible hydraulic system.
Hydraulic trailer jack questions and answers
Does this jack include a hydraulic power unit?
No. This is the jack-only listing. Supply a compatible hydraulic system or choose a complete powered jack kit from our hydraulic trailer jack collection.
Can I use this jack with my single-acting dump-trailer power unit?
Yes, with the appropriate X-Block kit and a compatible installation. Purchase this jack in your preferred mounting configuration, then add the Poly Tank or Steel Tank X-Block Kit. The adapter supplies the directional control needed for powered jack extension and retraction.
Do I need another hydraulic hookup kit if I buy this jack and the complete X-Block kit?
No additional hydraulic hookup kit is needed for the intended compatible setup. The complete X-Block kit includes the adapter, selector valve, hoses and connection fittings. Verify the tank-return fitting, hose reach and mounting arrangement for your installation.
What is the benefit of dual counterbalance valves?
They provide load-control functions for both cylinder sides, helping maintain the jack’s extended or retracted position. They also control load-driven movement during operation, rather than simply opening an unrestricted return path.
Do the valves help prevent the jack leg from drifting down during travel?
Yes. The dual counterbalance arrangement helps resist unintended extension when the jack is retracted, as well as unintended retraction when it is extended. Follow the manual’s transport and operating instructions and keep the jack and hydraulic components properly maintained.
Is a 24-inch-stroke jack always a better choice?
No. Stroke is only one part of the installation. Compare lifting reach, retracted ground clearance, mounting height and above-frame projection. This jack provides 20 inches of travel; confirm that its dimensions suit your trailer and required coupling height.
Can I install the jack without welding?
Choose the bolt-on version when its mounting arrangement matches your trailer or a compatible transition adapter. Confirm the hole pattern, dimensions and structural support before installation.
Does buying two jacks automatically double my installation’s capacity?
No. Load sharing, mounting strength and hydraulic arrangement determine how the load is carried. Select a suitable dual-jack system and remain within the applicable jack, trailer and component ratings.
Manual, warranty and installation video
- Download the Primary Mover 12K Hydraulic Trailer Jack Manual
- View warranty coverage and terms
- Learn about dual counterbalance valves
Need help choosing your jack setup?
Use our Jack Kit Selector or browse hydraulic trailer jacks and kits to compare jack-only, add-on and complete powered configurations.
Call 985-888-6554 or email sales@primarymover.com with your trailer application, mounting dimensions and photos of your existing power unit.