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The often-forgotten stock trailer

Michael J. Thomas for Progressive Dairyman Published on 31 December 2016
Tires had equal tread at the start of the road trip

It is that time of year again when we start to think about catching up on maintenance.

One of the items we easily overlook are the stock trailers we use periodically throughout the year – and which otherwise sit parked out of the way, silently waiting for the next time we need them.

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Use a systematic process to examine and service the trailer. Beginning with the hitch, check to be sure there are no loose bolts or broken welds. Examine the latch to make sure it functions properly. Latches can become broken or bent in the course of everyday use and should be repaired or replaced to avoid an accident.

Check the safety chains to be sure they will function properly. Check the trailer-ball socket for grease. The most common practice for maintaining grease in the socket is to apply grease to the ball of the tow vehicle before hooking to the trailer.

Inspect the frame and body panels (interior and exterior) for rust or broken welds. Pay special attention to door latches and safeties.

To inspect the lights and electric brakes, you will need to attach the tow vehicle to the trailer. Once the tow vehicle is attached to the trailer, turn on the headlights of the tow vehicle. Walk around the trailer and check to make sure the marker lights and taillights are working correctly.

A test light can be used to check power in the tow vehicle power outlet

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If the marker and taillights are not working, use a multi-meter or test light to check the electrical outlet of the tow vehicle for power. If you have no power at the tow vehicle, check for corroded connections in the outlet and wiring problems in the tow vehicle.

If you have power at the tow vehicle power outlet, check for corroded connections in the trailer wiring plug, damaged wiring in the trailer wiring harness or bad ground-wire connections in the trailer.

If some of the lights work, but not all of them, begin checking bulbs in the non-functioning marker or taillights. If the bulbs are good, check the wiring to the individual light affected.

Next, activate the turn signals and check to make sure they are working properly. If one or more fail to operate properly, perform the previously mentioned process to identify and correct the problem.

To check the brake lights and electric brakes themselves, you will need another person to help you. With a helper activating the brake pedal, verify that the brake lights are functioning properly.

After verifying the proper function of the brake lights, verify that the trailer brakes are working. There is a quick way to determine if the electric brake units are receiving power to the magnets.

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While the helper is activating the brake on the tow vehicle, listen to each of the brake units. If the magnet is receiving power, you will hear a soft but distinct hum. If you do not hear this, perform the same procedure mentioned earlier for troubleshooting electrical issues in the lights. It is not uncommon to find a bad connection, ground or broken wire.

We now move to one of the most vital series of components of a stock trailer, and one that is easily overlooked: tires, wheel bearings and the physical components of the brake system. It can be hard to judge the life left in a tire based on the tread.

Many tires that appear to have much life left may be 10 or more years old. While the tread may appear to be fine, weather checking – damage from oxygen and sunlight – has hardened or cracked the rubber. If the tires are old or beginning to crack at the sidewall, replace or carry adequate spares. Always make sure tires are properly inflated.

Heavy trailers should have a minimum of 10-ply tires inflated to 70 to 80 psi. Low air pressure will cause the tires to heat and come apart.

In order to service the bearings and inspect the brake drums, shoes and activation mechanism, you will need to remove the wheel. Remove the dust cap to reveal the castle nut holding the bearings and hub on the spindle.

Remove the castle nut and carefully work the hub off of the spindle. The outer bearing may fall out of the hub as it comes off of the spindle. Be careful to catch it and keep it clean.

If the inner bearing and grease seal remain on the spindle, use a chisel and carefully work them loose, making sure not to score the spindle where the bearing or seal seat. Once you have removed the inner bearing and seal, clean and inspect the condition of the spindle.

Run your fingernail along the length of the spindle from the seal seat to where the outer bearing rests. If the surface is smooth, the spindle is good. If you feel ridges, replace the spindle.

At this point, you have exposed the brake shoes and drums. Check the drums for excessive wear, cracks or scoring. If the drums are damaged, replace the drum/hub before reassembling.

Next, inspect the brake shoes. If they are coming apart or the rivets are wearing into the drums, replace before continuing. Also inspect the mechanical components of the brake activation system, including the electric magnet. If any of these components are worn, bent or broken, replace them.

After repairing the brake system, or verifying that it is in serviceable order, inspect the condition of the bearings and seal before reassembly. If the seal appears cracked or rotten, replace it. Seals are inexpensive. If in doubt, replace the seals. Clean the bearings in solvent and inspect them for damage.

Make sure the cages are not dented or damaged. Look closely at the rollers for scoring or discoloration – an indication that they have been hot. Run your fingernail over any suspicious blemish. If you feel a ridge or groove, replace the bearing.

Wheel bearings can be matched at your local auto-parts store. Check the inner and outer races for discoloration and scoring. If they are damaged, replace them.

Pack the bearings by hand before reassembling. Cup a glob of high-quality wheel bearing grease in the palm of your hand and grip the bearing between the thumb and fingers of your other hand so that you can look through the hole in the center.

Pat the edge of the bearing repeatedly into the grease with a downward scoping motion. You will see the grease working into the bearing. Work the bearing around in a circle until you have packed all of the rollers in the bearing.

Finally, be careful not to overtighten the castle nut when you reinstall the hub. Run the castle nut up snug, working the hub back and forth as you go. Back the nut off, wobble the hub again, and then run it up snug.

It is important not to run the nut up so tight that there is much resistance when you rotate the hub. Next, back off the castle nut until you can line up the cotter pin or tab in the tang washer. Re-install the dust cap and wheel.

A good annual inspection can save you from some unwanted downtime on the side of the road or a terrible accident. Take the time to inspect and service, and then roll on with confidence – knowing the status of your stock trailer. end mark

PHOTO 1: These tires had equal tread at the start of a road trip, but 90 miles into the haul, the tire on the left shed the outer layer. Tread depth does not always indicate correct tire wear. 

PHOTO 2: A test light can be used to check for power in the tow vehicle power outlet. Photos by Michael Thomas.

Michael J. Thomas is a freelancer, stock producer and farm mechanic from Salmon, Idaho. Email Michael J. Thomas.

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