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Wire Rewind Stuck - LitterMaid Repair


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A tensioned wire feeds power to the rake motor in the LitterMaid. The tensioning is performed by a piece of spring steel on a roller that moves back and forth under the circuit board and battery compartment. The spring steel is subject to metal fatigue and will eventually break (after about three years, in my case). The wire will not be rewound into the compartment and can become caught in the rake, and may break.

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Unless you can get spare parts from the manufacturers of LitterMaid, there is no way to repair this tensioner. However, with an elastic band and a piece of electrician's tape, you can jury-rig an external tensioner for the wire that works just fine.

  • Run the LitterMaid so that the rake moves down to the waste receptacle, and then switch the power off so the rake is left there.
  • Wrap the elastic band around the wire and then back through itself, so you have a loop of elastic hanging from the wire.
  • Cut a 4-inch length of electrician's tape, pass it through the elastic loop, and use it to tape the loop to the side of the LitterMaid.
  • You'll have to experiment with the position of the elastic on the wire, and with the taping location, so that the wire is drawn safely out of the way of the rake when it runs.

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Comments

A replacement spring looks to be available at the McMaster-Carr website under 'Stainless Steel Constant-Force Springs':

www.mcmaster.com

Search for part number 9293K44, currently priced at $5.17 each. Their site has just about everything mechanical. The littermaid motor and other standard parts (not the molded plastic parts) are probably available there too; just check the model numbers.

Posted by: Phil | November 28, 2006 at 11:26

Inspired by your use of an elastic band to deal with a 'stuck' motor power wire, I performed a rather more ambitious repair.

I took out the four screws (two on each end) on the side of the machine that held on the battery and controller assembly, which was then easily removed by pulling straight up. (It remains tied to the rest of the machine by the control and sensor wires on both sides.)

I then took out the three screws inside the battery compartment and the single screw on the underside of the battery and controller assembly, right next to the pulley that the rake power wire runs around to enter the assembly.

This allowed me to take the flat plastic piece that the pulley is mounted in and slide it out of the battery and controller assembly, revealing the controller circuitry under it, and the rake power wire tensioner mounted on its backside.

There I discovered that the wire is held under tension by a coiled steel band spring that wraps itself around a spool at the end of the plate as the wire returns to be stored.

Or, at least, it would if the spring in my unit hadn't snapped in two about half way along its length, leaving the pulley that the slack wire is supposed to be held tight by flopping around loose between the mounting plate and the underside of the battery compartment.

I repaired this by:

1) I removed the broken pieces of the tensioning spring. (The piece that was still wrapped around the spool just pulled off, as the only thing holding it there was its own coiled shape. The piece mounted to the tensioner pulley bracket was attached by a simple pop-rivet, which I removed by drilling it out with an eigth-inch drill bit.)

2) I replaced the spring with an approximatly 18" piece of light-weight oval elastic cord (purchased in the craft department of Wal-Mart in a 2.5 yard blister pack.)

I did this by tying one end of the elastic to the hole through the bracket of the tensioner pulley that the original spring had been riveted to, passing it around the spool that the spring originally used to wind itself up onto, and back up to a small hole (3/32") that I drilled through the mounting plate next to the pulley on the other end of it where the wire passes through it. (I dragged the elastic thorugh the hole with a loop of thread, and tied the elastic into a stop-knot on the other side of the plate.)

This gives all appearances of being a complete functional and visually indestinguishable replacement for the original spring, Not to mention being cheap and fast!

See the attached photo for the appearance of the repaired mechanism.

Posted by: Ross | November 05, 2006 at 14:02

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