park model trailers and mobile homes. The first tip-outs were not very large, the size of a dinette, with a couch size tip-out being added later. Then, because we are Americans who always think bigger is better, the industry produced the double tip-out. That thing was so big and so heavy that winches had to be used on the opposite wall in order to tip the room in or out.
Tipping in and out a giant room was obviously not the answer, so the industry moved to a box extension to expand the living area. The designers, realizing the benefits of expanding living space this way, were pushing the envelope and creating box extensions that included space for the dinette, couch, and even more.
Pushing this big old room in and out by hand didn't seem like the answer, so our industry experimented with all sorts of drive systems including chain drives, various hydraulic and gear drives, and screw jacks similar to the ones we currently use for fifthwheel front leveling.
Several power, fit, and reliability problems prevailed over the years. Just talk to someone who has owned an older slide-out room fifthwheel and they can unusually spend hours telling you horror stories about gaskets that leak, rooms that don't fit, rooms that get stuck in or out, or rooms that "rack" (racking is when the room starts moving at an angle other than 90° to the sidewall) while being moved.
Through my experience in the US Navy Submarine Service and from my long time interest in the aircraft industry, I learned that if you wanted to move a heavy load reliably, perhaps hydraulics would be a good reliable answer. But hydraulic components have a drawback compared to simple mechanical systems; they are very expensive. Luckily for us, about 6 years ago we established a relationship with an outside supplier of a hydraulic system who had perfected a simple method of moving slide-out rooms in and out. Instead of using a double cylinder, they used a single one, thus reducing cost and weight. Using a simple system of aircraft cable and pulleys mounted under the floor to tie the ends of the slide-out together, they developed a system that runs the room straight in and out without racking. And it really did work just great.
In fact, over the course of the last five years our customers have had "O" field operational problems with our new hydraulic system. We did catch four problems with high pressure oil fittings that had been cracked during exposure to our production process. These problems, however, were corrected prior to delivery to our customers. One of our customers however did have a problem after he took his new 33RK GS model home to Mississippi. He was at a church picnic and was showing off how smoothly and powerfully his slide-out room would run in and out while loaded with church picnic goers when . . . . drip, drip, drip. One of our production fellows was careful enough to run a screw through one of his hydraulic lines. We sent a new line which fixed the problem. Even though that particular problem occurred in the field, it was really not a field operational problem since it was caused by us at the factory. Needless to say, this kind of record proved to us that we did offer our customers a tough and reliable slide-out system.
Now we are always on the lookout for ways to improve our product, and if we can save some money at the same time . . . then, why not? Last year we were approached by a producer of a mechanical rack and pinion system which seemed to be even more simple, lighter weight, smaller, and the big one . . . . cost less than our hydraulic system. The system had been well tested by several of the largest RV manufacturers, so we switched to the mechanical system.
Then one of our customers called from Memphis, Tennessee. He had a burnt out motor. Three days later a new motor was installed under warranty. Then we got a similar call from Texas. Then we got a call from one of our customers who had forgotten to lock his room in place for travel. He went over a railroad track and the room drive gear on one side had jumped over one of the flat rail cogs. Now the room had racked and no longer fit into the gaskets.
We weren't used to our customers having these kind of problems because hydraulic systems always lock automatically when idle and hydraulicly unlock themselves when they operate. You don't have to remember anything. With a hydraulic system, the customer doesn't have to worry or remember about whether his system is locked or not. (My memory doesn't seem to be getting better with time, either). Customer field operational problems with purely mechanical systems were now starting to appear regularly!
These three customer operational problems were three more than we had ever had over the last 5 years with the more expensive but, as it turns out, more reliable hydraulic system So, with bitter experience as the best teacher we have gone back to the basics. Hydraulic operating slide-out systems are once again part of the GS specification for KISS. We guess that sometimes you have to spend a bit more for a good KISS.
