How an in-wall slide is built and moves

An in-wall room hangs on gear racks screwed to its sides, driven by one motor per side standing in an H-column at the wall opening. A torque shaft ties the top and bottom of each side together; only the controller ties the two sides together.

The short version

• Each side: an H-column screwed and sealed to the sidewall, a motor on top, a torque shaft down the middle with a spur gear at each bearing block.
• The spur gears drive gear racks screwed to the side of the room: upper and lower, plus a middle rack on some rooms.
• The room floor rides on floor rollers at the opening. Nothing runs under the floor or through the frame.
• There is no shaft between the two sides. The controller keeps them even by counting hall-effect pulses from each motor.
• Plugged-in motors hold the room. Unplugged or disengaged, nothing holds it.

What's inside each column

Each side of the room has one H-column: an aluminum extrusion that stands in the wall opening, screwed to the sidewall and sealed along its inside edge. The motor drops into the top of the column and is held by a single retention screw on the outside, near the top and usually under the bulb seal.

Below the motor, a coupler joins the motor shaft to a torque shaft that runs down the column from the upper bearing block to the lower bearing block. Each bearing block carries a spur gear, so one motor turns the top and bottom gears on that side together. Lippert builds torque shafts in aluminum, steel and hex versions, and the hex shaft takes a hex coupler.

• H-column: fastened and sealed to the sidewall at the opening
• Motor: top of the column, one retention screw, 300:1 or 500:1 gearing
• Coupler: motor shaft to torque shaft
• Torque shaft: runs between the upper and lower bearing blocks
• Bearing blocks: each holds a spur gear and a guide shoe
• Gear racks: upper and lower on every room, a middle rack on some

How the room hangs on the racks

The gear racks are screwed to the sides of the room with #10 pan head screws, and their ends tuck inside the bulb seal on the T-molding. Each rack is captured three ways: a hook with a plastic shoe rides a slot on the rack's top edge, the spur gear meshes with the teeth, and a V-roller rides a groove on the bottom edge.

The lower rack has an angled lip that butts against the bottom of the room, and that's how it gets located during a rebuild. Racks come in a standard profile and an inverted profile, and with different end notches: 1.56 in is standard, with 1.0, 1.75 and 2.0625 in as custom notches. Those aren't interchangeable, so photograph the variant tag on the H-column and the rack end before you order anything.

What carries the weight

There are no tubes, rams or actuators under the floor. The room floor rides on floor rollers at the bottom of the opening, and the racks and columns carry and drive the sides. Everything that wears is in the wall opening: rollers, racks, shoes, V-rollers and seals.

Lippert's roller check is simple: the rollers should roll under the room floor, not dig into it and not spin free. A roller digging in, or a wiper seal caught in a roller, shows up as drag, stalling and code 5.

How the two sides stay together

Nothing mechanical connects the left column to the right column. Each motor has a hall-effect encoder, and the controller (Lippert sells it as a dual-motor synchronous velocity controller) counts the pulses from each motor and holds the two sides to the same speed and position.

The count is referenced to the ends of travel. In Lippert's words, if the room doesn't reach full extension or full retraction, the controller loses its zero point and the sides drift apart. That's why owners are told to keep holding the switch a few seconds after the room stops.

Top to bottom on one side is mechanical, through the torque shaft. So a room can go wrong two ways: out of sync, where one side is ahead of the other and the controller can fix it, or out of time, where the top or bottom of one side is ahead and only re-meshing that column's racks fixes it.

How it stops and what holds it

There are no limit switches. The controller stops each motor when it stalls at the end of travel, so both motors should shut off on their own while the switch is still held. Electronic override turns pulse counting and stall detection off, which is why override runs unsynced.

Plugged-in motors hold the room. Lippert's manuals say unplugging both motors releases the brake so the room can be pushed by hand, plugging them back in applies it, and the RV must not be moved unless the motors are plugged in.

Careful: With the motors unplugged or disengaged, nothing holds the room. Plug them back in or travel-lock the room before the coach moves.

On the job

1. Confirm it's in-wall: a column in the wall opening on each side, gear racks on the room sides, nothing under the floor.
2. Find the Lippert variant tag on the H-column and photograph it. It dates the system and identifies the parts variant.
3. Run the room out and watch both ends from outside. Note which side leads, and whether the top or bottom of either side leads.
4. With the room out, look at all racks: debris, metal shavings, screws not flush, a seal caught.
5. Check the floor rollers and V-rollers: rolling, not digging in, not spinning free.
6. Find the controller and read the LEDs before you unplug or reset anything.

Numbers

• Motor gearing: 300:1 standard, 500:1 high torque (Lippert in-wall motors 236575 and 287298)
• Standard gear rack notch: 1.56 in; custom notches 1.0, 1.75 and 2.0625 in
• Gear rack screws: #10 pan head
• Motors per room: 2 (Motor 1 and Motor 2), one per side, on every Lippert in-wall controller documented

Shop tip

Before you diagnose, stand outside with a tape and measure how far the room sticks out at the top and bottom of both ends. Those four numbers tell you right away whether you're chasing sync (one end ahead) or timing (top and bottom of one end different).

Where this comes from

• Lippert, In-Wall Slide-out Owner's Manual, CCD-0001602, Rev 07.12.18 and Rev 04.19.23: components, parts pages, gear rack notches
• Lippert, 13398-C1/C2 Operation and Service Manual (Schwintek In-Wall controls B, C, C1, C2): rack hook, gear and V-roller arrangement, pulse counting
• Lippert, In-Wall Slide-Out Assembly Manual, Rev 05.12.21, pp. 2 to 4: torque shaft, bearing blocks, timing
• Lippert, In-Wall Slide-out Service Manual, Rev 06.14.2016, pp. 10, 13, 22, 27: floor rollers, harness colors, assembly diagram, torque shafts and couplers
• Lippert blog, Retiming a Schwintek slide out and preventing syncing issues, May 1, 2020: zero point

Try it on a service call

Put the lesson to work on a hands-on troubleshooting case.

• One side of the slide won't move