Free-standing 4" single jacks with a horizontal shaft are commonly used on heavy-duty bumper pull trailers. This setup is one of the simplest Trailer Gearbox installations: remove the manual crank handle, slide the correct drill-powered trailer GEARBOX onto the jack shaft, secure it with the included standard bracket and snap pin, and you’re ready to operate your trailer jack with a cordless drill.

Single 4" horizontal-shaft jacks mounted against a front panel are commonly found on gooseneck enclosed trailers, stock trailers, and horse trailers. This setup usually has two Trailer Gearbox installation options depending on how the jack handle and extension shaft are arranged.

At the Jack:

Option 1: Remove the handle and extension shaft, then mount the GEARBOX directly to the jack using the included standard bracket.

Option 2: If the Jack is mounted flat against the trailer brace and does not allow a standard bracket, an OVER/UNDER BRACKET may be used to brace the gearbox.

At the Handle:

Option 1: For a quick and versatile install, remove the handle from the extension shaft, install the GEARBOX using a HANDLE BRACKET, then slide the gearbox onto the extension shaft and pin it in place.

Option 2: For a purpose built install, and a 1/2" hole above or below your jack shaft and install your GEARBOX with a PIN BRACKET. The pin slides into the hole in your panel and prevents rotation.

Externally mounted dual jacks are one of the most common jack configurations found on gooseneck trailers. “External” means the jack bodies are visible and accessible on the outside of the trailer, rather than hidden behind a stanchion, panel, or enclosure.

Because the jack body is easy to access, installation is usually straightforward: remove the existing handle, slide the Trailer GEARBOX onto the jack shaft with the included standard bracket installed, and secure it with the snap pin. The factory connecting rod between the two jacks will run both simultaneously as usual.

Bracket Note: If your jack body is welded flat against the trailer and there is not enough clearance for the standard bracket leg to wrap around the jack, you can remove the standard bracket and run the gearbox without it. In this setup, the close fit against the trailer panel acts as the anti-rotation support and keeps the gearbox from turning while in use.

Internally mounted jacks are less common and usually found on older trailers. “Internal” means that the jacks are hidden behind a stanchion, panel, or enclosure, and generally not accesible.

Because the jack body is not accessible, an accessory bracket is usually required.

Option 1: For a quick and versatile install, remove the handle from the extension shaft, install the GEARBOX using a HANDLE BRACKET, then slide the gearbox onto the extension shaft and pin it in place.

Option 2: For a No-Modification dedicated bracket, Install the GEARBOX with an OVER/UNDER bracket using the adjustable top and bottom tabs to interface with the stanchion of your trailer.

Option 3: For a purpose built install, and a 1/2" hole above or below your jack shaft and install your GEARBOX with a PIN BRACKET. The pin slides into the hole in your panel and prevents rotation.