Most drivers are well aware of how important it is to give their tractor and trailer a good pre-trip inspection. However, many drivers may overlook the converter gear dolly or not give it enough attention during their pre-trip inspection. The dolly is a vital piece of equipment for securing your additional trailers and is responsible for relaying the electrical and air connections to your trailers. An improperly maintained dolly could cause you to lose control due to bald tires or inoperable trailer brakes. A damaged dolly could also cause you to drop a trailer or not have any tail lights. These are all potentially dangerous situations that can be avoided by performing a good pre-trip inspection on every dolly you use.

The dolly pre-trip inspection is very similar to the inspections you already perform on your tractor and trailers.

To begin the dolly pre-trip inspection:

• Look for any obvious defects such as missing or broken parts, cracked wheels and damaged or flat tires.
• Make sure that the tires are not rubbing against each other.
• Confirm that the tires have more than 2/32” of tread depth. (Be careful when feeling around the tires, because wires from the tire’s belt may be exposed.)

Check the lower fifth wheel:

• Make sure no parts are missing or broken
• Look at the frame to make sure the fifth wheel is properly secured and no welds are cracked.
• If the dolly does not have a grease-free lower fifth wheel plate, look to see if the plate needs more lubrication.
• Make sure the release pin moves freely.
• Check the ring hitch for any signs of cracking or damage.
• Observe the air and electrical lines and ensure that none of the lines are cut or abraded.
• Check the fittings and electrical plug for signs of damage.
• Check the brake release before you move the dolly to make sure the wheels will move freely. (There may be different types of releases, such as levers or buttons located on the dolly frame.)

Connect the dolly to your first trailer and prepare to couple the second trailer:

• Check that the pintle hook is free of damage and holding securely.
• Make sure your safety chains are connected.
• Confirm that your air lines and electrical line are properly connected and are secured where they will not be damaged.
• Check the trailer apron and kingpin for signs of damage.
• Couple the second trailer.
• Visually check to make sure that the kingpin is secured in the lower fifth wheel.
• Ensure that the first trailer’s air valve is open and the dolly air tank drain valve is closed.

Move to the back of the rear trailer.

• Crack open and then close the rear trailer’s air valve to ensure that air is flowing all the way through the system. You should hear air escaping when you crack the valve and it should stop when you close it.

Move to the cab of your tractor.

• Turn off the parking brake on your tractor, but do not supply air to the trailer.
• Use the tractor to lightly tug on the trailers to ensure that the brakes are working. The trailers should not move during this test.

Repeat the above steps for each dolly and trailer.

Have a safe trip!