|
|
RV Doctor ColumnRV Doctor #262 Dear RV Doc, I have purchased a used 1970 travel trailer in okay condition. If the frame, wheels, brakes and other basic hauling components are in reasonable order, I plan to renew the interior for weekend trips to the beach and camping. It is a 20-foot Volunteer brand and I can find nothing about the manufacturer anywhere. I was told it has electric brakes, but automotive brake repair places tell me they are not equipped to work on these brakes. Before I take it to an RV dealer to have the brakes checked, what should I know about electric brakes and the maintenance they may need? Paula Leonardo, (Tampa, FL) Paula, electric brakes resemble automobile drum brakes in that two components, shoes and drums, interact to apply braking force. There are two shoes in each brake assembly mounted on a backing plate secured to a stationary part of the axle. Braking force is applied by the shoes being forced outward and pressing against the drum wall. The harder the shoes press, the greater the frictional drag exerted on the spinning wheel and quicker the stopping action. Here the similarity with auto drum brakes stops. Electric trailer brakes are operated by 12-volt DC electricity originating at the tow vehicle battery. At the heart of each electric brake assembly is the magnet. When the magnet is energized by a controller mounted in the tow vehicle, it is attracted to the armature, a metal disc fixed inside the drum that spins with the drum. As the magnet moves laterally toward the armature, it is pulled in the direction of motion causing a lever to push the shoe against the drum. Both shoes are linked so that the movement of one activates the other. Braking continues as long as the magnet continues to receive the appropriate voltage from the tow vehicle. Maintenance on electric trailer brakes involves basically three different areas: inspection, cleaning and adjustments. Your trailer brakes must be inspected and serviced at yearly intervals or more often as use and performance dictate. The inspecting technician should look for worn shoe linings. Replace shoes if the lining is 1/16" thick or less. Replace them also if they are saturated with grease or oil or are cracked, gouged or if the lining has become separated from the shoes. Replace the magnets if they show signs of uneven wear. It is wise to replace all the same items of the same axle even if only one side necessitates replacing. If, for instance the right side magnet is worn, but the left side is okay, replace them both. Keep all like components on the same axle, the same age. The drum surface should be inspected for excessive wear or heavy scoring. If the wear marks are worn more than .020" or the drum has worn out of round by more than .015", then the drum surface should be turned. If scoring or other wear is greater than .090", the drum must be replaced. Electric brakes also require periodic adjustment to keep the shoes properly spaced. The main symptoms of brakes in need of adjustment are brakes that get hot while driving down the road, (the shoes are dragging against the drum), or brakes that simply will not hold. Adjustment is simple, but important. Here are the procedures: jack up and properly support the trailer so that the weight is off the wheel and remove the plug from the back side of the backing plate. Slip the tip of the adjusting tool into a notch in the star wheel then ratchet and rotate the star wheel to expand the shoes against the drum (rotation may be clockwise or counter-clockwise, depending on the brake manufacturer). Expand the shoes until you cannot rotate the tire any further. This centers or seats each shoe evenly against the surface of the drum. Then back the adjustment off in the opposite direction until the wheel turns freely but has a very slight drag during rotation. Replace the plug to keep dirt and moisture out. Repeat this process on all remaining brakes. Dear Gary, unfortunately a squirrel decided to take up residence in our 1990 Fleetwood motorhome. The little bugger didn't make it and neither did our screens that he tried to chew his way through. My husband is having a heck of a time trying to remove the screens in order to repair them himself. Is there a secret to popping out the screens? Please help before my husband shoots every moving squirrel on the property! June Hart, (Onondaga, MI) June, normally the screens simply lift up and out. There should be two small, plastic clips attached to the bottom and top of the screen frame which glide on the extruded aluminum frame of the window. It might be necessary to carefully bend the center of each vertical side of the screen frame as you exert pressure to remove the it. Replace any broken clips if you find any. They are available from any well-stocked RV parts center. Additionally, to thwart future efforts of the wildlife, replace the fiberglass material with aluminum screening. Dear RV Doctor, I recently read an article you wrote regarding tire damage by ultraviolet rays; it was very informative. I was talking to another RVer recently who told me that wiping the sidewalls with transmission fluid will help prevent sidewall cracks due to ultraviolet rays. My question to you is can this be possible? He claims that the properties of transmission fluid and the tires are very similar and that's why it works. I would appreciate your comments on this since I just purchased six new tires for my rig after the originals were so cracked that I felt it would be dangerous to drive on them. Carlo Coppola, (Las Vegas, NV) Carlo, Negative on the tranny fluid Carlo. This will cause the tires to dry out excessively. As the oil evaporates it will deplete all the natural surface waxes blended in during manufacture. Avoid any product that contains petroleum-based or silicone substances. There are some nice products available in the aftermarket that can block UV rays and protect against ozone damage, but they typically will leave the tires with a dull sheen rather than the nice shiny surface most people like; plus they are probably less expensive. Cover the tires when not in use. The flexing and bending they receive while driving will bring the waxes back to the surface. Dear RV Doc, our RV must always remain outdoors. What is the best protection? Are RV covers really a good idea or not? Is just leaving it exposed to the elements going to create any problems we should be aware of? Linda Lakey, (Everett, WA) Linda, I have always been a fan of the total coach cover. There are quite a few on the market so get some prices for your length of RV. Look for quality, not simply price. Indoor and underground facilities are other alternatives. The main thoughts should center on freeze damage and moisture prevention. I only know of one underground storage facility in Pennsylvania, but would appreciate hearing of others if any are located in other parts of the country.
|
|
|
[ Home ] [ Ask the RV Doctor ] [ RV Doctor Column ] [ Memorandums ] [ Interesting Articles ] [ Product Spotlight ] [RV Service Technician Training ] [ Seminars ] [ Links ] [ Gary's Bio ]
Send your questions and comments to:
gbunzer@cox.net |
|