How a Trailer Jack Works

A trailer jack raises and lowers the trailer’s tongue or front end by turning rotational input—via a hand crank, electric motor, or hydraulic pump—into straight-line lifting. Inside the jack, a screw-and-nut or gear-driven mechanism extends or retracts an inner tube (or drop-leg), moving the coupler up or down to hitch, unhitch, or level the trailer while supporting the tongue weight.

What a Trailer Jack Does

At its core, a trailer jack supports the trailer’s tongue weight and precisely adjusts height so the coupler can seat onto or lift clear of the tow vehicle’s hitch ball. It also stabilizes the trailer during loading, storage, and campsite setup. Although robust, a tongue jack is designed to carry vertical tongue load—not to lift the entire trailer for wheel service or to tolerate strong side loads.

Inside the Mechanism: How Lift Is Created

Manual screw-drive jacks

Most manual jacks use a coarse acme screw and captive nut inside a telescoping outer tube. Turning the crank (side-wind or top-wind) spins the screw through reduction gears, converting rotary motion into linear extension. The large thread pitch provides mechanical advantage, while thrust bearings handle axial load as the inner tube raises the trailer. A footplate or caster spreads the load onto the ground.

Electric power tongue jacks

Electric jacks use a DC motor and gearbox to turn the same kind of screw drive at the push of a switch. Integrated limit switches prevent overtravel, and internal fuses or breakers protect the motor. Many include an LED work light and a manual override socket for a hand crank if power is lost.

Hydraulic and landing-gear systems

Heavy trailers (e.g., fifth-wheels) may use dual “landing gear” legs powered by an electric motor driving both screws or a hydraulic pump feeding cylinders. Hydraulics deliver smooth, strong lift with a control valve; screws hold position mechanically without continuous power.

Drop-leg and quick adjustments

Drop-leg designs add a nested inner leg with pin holes. Pulling a spring pin lets the leg free-fall to the ground, then the screw drive handles the last few inches of fine lift. This speeds setup and reduces cranking.

Footplates vs. caster wheels

A flat footplate maximizes stability and resists rolling on soft ground. A caster wheel allows short, light trailers (like small boat or utility rigs) to be nudged by hand but reduces load capacity and is more vulnerable to side loads or ruts.

Key Components You’ll Find on Most Jacks

The following list outlines the typical parts that make a trailer jack function and how each contributes to lifting and stability.

• Outer tube and inner leg: Provide telescoping structure and guide lift travel.
• Screw and nut (acme thread): Convert rotation into linear motion for lifting.
• Gear set and bearings: Create mechanical advantage and manage thrust loads.
• Crank handle or motor/gearbox: Supplies rotational input to the screw.
• Footplate or caster: Spreads load onto the ground and improves stability or maneuverability.
• Mounting interface: A-frame 3-bolt pattern, pipe/plate weld-on, or side-mount swivel collar.
• Weather seals and grease fittings: Keep contaminants out and lubrication in.
• Drop-leg pin (if equipped): Enables quick height changes before fine cranking.

Together, these components ensure the jack can lift smoothly, hold position securely, and withstand outdoor use with proper mounting and maintenance.

Common Types of Trailer Jacks

Different trailer designs and weights call for specific jack configurations. Here are the most common types and where they fit best.

• A-frame tongue jack: Bolts through the coupler’s 3-hole triangular pattern; common on travel and utility trailers.
• Side-mount swivel jack: Clamps to the frame rail and swings up for travel; typical on light utility and boat trailers.
• Pipe- or plate-mount jack: Welded receivers for heavier-duty applications on equipment trailers.
• Drop-leg jack: Adds a pin-adjustable inner leg to shorten cranking and increase lift range.
• Electric power tongue jack: Motorized lift for frequent hitching or heavier tongue weights.
• Landing gear (dual jacks): Paired front legs on fifth-wheels and large campers for high capacity and stability.
• Stabilizer jacks: Light-duty corner jacks used to steady, not lift; not for hitching or major weight-bearing.

Selecting the right style ensures adequate capacity, correct mounting, and efficient operation for your trailer’s size and use case.

Operating a Trailer Jack: Step-by-Step

Unhitching (disconnecting from the tow vehicle)

Follow these steps to safely separate the trailer from the vehicle using the jack, minimizing strain and avoiding roll-away.

1. Park on firm, level ground; set the tow vehicle in Park with the brake on and chock the trailer wheels.
2. Lower the tongue jack foot to the ground; use the drop-leg if equipped for quick contact.
3. Unlock and open the coupler latch; remove safety chains and unplug the wiring harness.
4. Crank or power the jack up to raise the coupler off the hitch ball, watching for clearance.
5. Once clear, pull the tow vehicle forward slightly and verify the trailer is stable on the jack.

By transferring the tongue weight onto the jack before moving the tow vehicle, you keep loads predictable and reduce wear on both coupler and hitch.

Hitching (connecting to the tow vehicle)

These steps help align the coupler and set proper height without overstressing the jack or coupler latch.

1. Chock trailer wheels; back the tow vehicle so the ball aligns under the coupler.
2. Use the jack to lower the coupler onto the ball until it fully seats; close and lock the latch.
3. Attach safety chains in a crisscross pattern; connect the breakaway cable and wiring.
4. Retract the jack fully; stow the drop-leg or swivel the jack up and pin it for travel.
5. Remove chocks last; verify lights and brakes before driving.

Lowering the trailer onto the ball rather than forcing alignment prevents damage and ensures the coupler latch engages correctly.

Sizing, Capacity, and Specs That Matter

Choosing the right jack depends on your trailer’s tongue weight, height needs, and environment. Consider the following factors when selecting or upgrading.

• Capacity: Match or exceed tongue weight (typically 10–15% of loaded trailer weight). Overhead capacity improves durability.
• Lift range: Ensure the extended height clears the ball when unhitching and the retracted height won’t bottom out.
• Mounting pattern: A-frame jacks use a standard 2-1/4 inch hole and 3-bolt triangle; confirm bolt circle and clearance.
• Side-load tolerance: Larger tubes and footplates resist flex; casters reduce side-load capacity.
• Corrosion resistance: Zinc, e-coat, powder coat, or stainless hardware matter for salt or marine use.
• Electric jack details: Duty cycle, current draw, weatherproof switchgear, and manual override make a difference.
• Ground interface: A wide foot or jack block prevents sinking on soft soil and spreads load.

Right-sizing avoids slow cranking, wobble, or premature wear, and ensures the jack can handle real-world terrain and loading.

Maintenance: Keeping the Jack Smooth and Safe

Routine care dramatically extends a jack’s life and reliability. Use this checklist to prevent binding and corrosion.

• Lubricate: Grease zerks if present; otherwise, apply light oil to the screw and gears per the maker’s guidance.
• Clean: Rinse salt and grime; keep the outer tube free of caked mud that abrades seals.
• Inspect: Check for bent tubes, cracked welds, loose bolts, and worn footplates or casters.
• Protect: Use a jack cover on electric units; keep the manual override tool accessible.
• Store: Retract fully when parked long-term and support with blocks to reduce exposure and side loads.

Simple, regular maintenance prevents most failures, particularly in wet or coastal environments where corrosion accelerates wear.

Troubleshooting Common Issues

When a jack misbehaves, these symptoms and remedies address the majority of field problems.

• Hard cranking or binding: Check for bent tubes, dry threads, or side-loading; lubricate and re-level the trailer.
• Jack won’t hold height: Worn screw/nut or stripped gears; replacement is often safer than repair.
• Electric jack dead: Verify fuse/breaker, ground, switch, and battery voltage; try manual override to isolate motor vs. power issues.
• Clicks but no movement: Gearbox damage or sheared pin; disassembly or replacement required.
• Sinking into soil: Add a larger base pad or block; avoid casters on soft ground.

Addressing root causes—misalignment, lack of lubrication, or electrical faults—restores reliable operation without over-stressing the mechanism.

Safety Limits and Best Practices

Always chock wheels before using the jack and avoid working under a trailer supported only by the tongue jack; use rated jack stands for service. Don’t exceed capacity or use the jack to pry or push the trailer sideways. Keep hands clear of pinch points around drop-leg pins and rotating cranks, and verify stability before disconnecting the tow vehicle.

Summary

A trailer jack converts rotational input into vertical lift through a screw, gear, or hydraulic system to support tongue weight and set coupler height for hitching, unhitching, and leveling. Picking the right type and capacity, operating with chocks and proper sequence, and maintaining lubrication and alignment deliver smooth, safe, and long-lasting performance.

Where is the jack point on a trailer?

He recommends using a floor jack and to make the jack contact the axles just inside the u-bolts. He states that this is where all the weight of the camper is on the trailer and it makes sense that this would be where you would want to place the jack. I personally use a bottle jack and an axle adapter.

What is the 60/40 rule on trailers?

The 60/40 trailer rule is a weight distribution guideline for safe towing that states 60% of the load’s total weight should be placed in front of the trailer’s axle, with 40% behind it. This distribution prevents dangerous trailer sway and instability, ensuring better control by keeping the majority of the weight over or forward of the axles. When loading, place heavier items closer to the front of the trailer and secure all cargo to prevent shifting.
 
Why the 60/40 Rule is Important

• Prevents Trailer Sway: Loading the trailer with too much weight behind the axle creates an imbalance that can lead to trailer sway or “fishtailing,” which is a terrifying and dangerous condition where the trailer starts to steer the tow vehicle. 
• Improves Stability: A properly balanced load provides stability for both the trailer and the tow vehicle, reducing strain on the engine and suspension. 
• Enhances Driver Control: With 60% of the weight forward, you maintain better control over your vehicle and trailer combination. 

How to Apply the 60/40 Rule

1. Load Heavier Items First: Place the heaviest items as far forward as possible. 
2. Distribute Weight Evenly: Distribute the weight side-to-side to prevent uneven load distribution. 
3. Secure Your Load: Once the weight is distributed, secure all items to prevent shifting during travel. 

What to Do If Sway Occurs
If you experience trailer sway:

1. Don’t Panic: Stay calm and keep your hands on the steering wheel. 
2. Slow Down: Take your foot off the gas and allow the vehicle to slow down naturally. 
3. Apply Trailer Brakes: Engage the trailer’s brakes to help correct the sway. 
4. Pull Over Safely: Once you have control, find a safe place to pull over and adjust your load to follow the 60/40 rule. 

How does a drop leg trailer jack work?

But uh so in terms of process it’s a really simple. Process just drop the leg. Find the nearest hole. Now we’re set up. And we’ll simply extend the leg. And raise the boat. Up.

How does a hand crank trailer jack work?

Most commonly, hitch jacks include a crank that turns internal gears, which then extends out of a metal shaft. The shaft raises the trailer off the ground so that it can be properly hitched onto the towing vehicle [source: Free Patents Online].