Coupling the Second Pup to a Converter Dolly on a Sloped Lot
At 06:20 you are at a Toledo shipper with a tractor, two 28-foot pups, and a converter dolly. The first pup is coupled to the tractor; the dolly is attached to the rear of the first pup. The second pup sits in a slot on a 2% slope, landing gear down, wheels chocked, trailer brakes set. Its kingpin plate is 1.5 inches higher than the dolly fifth wheel. There is a 6-inch curb 8 feet behind the second pup and 40 feet of clear space in front. The yard jockey reports the dolly's red emergency gladhand seal is missing and the blue service hose has a deep gouge exposing reinforcing cord near the fitting. You have a spare seal but no spare hose. The second pup is loaded to 18,000 lb; empty weight is 11,000 lb. Light rain, 34 F. You must decide whether to couple and depart.
1. How will you position and couple the second pup to the dolly, including handling the 1.5-inch height mismatch and the slope? What checks must be completed before you move?
Read the worked answer
Do not back under a mismatched trailer. First confirm both sides of the second pup are chocked and its parking brakes are set; on a 2% slope, chocks are the primary restraint, not the spring brakes alone. Use the landing gear to lower the trailer until the kingpin plate is just below the dolly fifth wheel, then align the dolly squarely with the trailer using the tractor and first pup, preferably with a spotter. Back under slowly, listen and feel for the fifth wheel to lock, then apply the trailer brakes and do two tug tests. Visually confirm the jaws are closed around the kingpin and the safety latch is engaged. Connect the red emergency line to red and the blue service line to blue, then the electrical cord. Build air pressure, check for leaks, raise the landing gear, remove the chocks, and test lights and trailer brakes. If the dolly or trailer moves during coupling, stop and reset rather than forcing it.
2. Can you replace the missing gladhand seal, tape the damaged blue hose, and depart? Explain the air-line consequences.
Read the worked answer
Replace the missing seal, because a missing seal will leak and may prevent proper air supply or brake release. Do not tape the blue hose. A gouge that exposes reinforcing cord means the hose is structurally damaged; tape is cosmetic and will not restore burst strength. The blue service line carries the application signal, so a failure can leave the second pup without service brakes or cause dragging brakes. The red emergency line supplies air and triggers spring brakes if it loses pressure, so a related failure can lock the trailer wheels unexpectedly. With no spare hose, the safe and legal decision is to call maintenance and not depart. A leak test after repair is required before the vehicle moves.
3. After coupling, what specific inspection and operational checks tell you the combination is safe to leave, and what would make you stop and uncouple?
Read the worked answer
Check the fifth wheel jaws and latch, the dolly drawbar connection, safety chains if used, air-line routing and clearance, electrical cord security, landing gear fully raised, and all chocks removed. Build system pressure, shut the engine off, and perform the static leak test; pressure should stay within the allowable leakage limit, and the low-air warning and spring brakes should operate. With the engine running, have a helper confirm the second pup service brakes apply and release, then test the tractor protection valve by charging and watching for proper trailer charging. Pull forward slowly and check in the mirrors that the second pup tracks and stops normally. Stop and uncouple if you see the fifth wheel jaw not closed, a hose rubbing or stretched at full articulation, a brake that will not release, or air loss beyond the allowable rate.