The lead trailer's lamps work, but the light cord at the rear trailer's socket is loose. How should a doubles driver assess this?
Correct answer: The rear connection still must be firmly seated and secured
The doubles walk-around includes firmly connected light cords at the trailers. A working lead-trailer lighting circuit does not prove the electrical connections farther back are secure.
Source: Georgia DDS Commercial Driver's Study Guide, 2023-2024 cover, retained PDF modified June 16, 2025; Section 7 > 7.3.1 - Additional Checks > Double and Triple Trailers / light cords; printed 62, physical 62. Current DDS-linked edition reviewed September 13, 2026. ↗
A converter dolly's air-tank petcock remains open after controlled positioning. What condition is required before the properly connected double is charged and cleared for travel?
Correct answer: Close the dolly's air-tank drain
The doubles procedure and inspection checklist require the converter dolly's air-tank drain to be closed for operation. That drain is distinct from the inter-trailer shutoff valves that pass air along the combination.
Source: Georgia DDS Commercial Driver's Study Guide, 2023-2024 cover, retained PDF modified June 16, 2025; Section 7 > 7.2.1 - Coupling Twin Trailers > Connect Converter Dolly to Rear Trailer; 7.3.1 > Double and Triple Trailers; printed 62, physical 62. Current DDS-linked edition reviewed September 13, 2026. ↗
A safely restrained double has normal tractor pressure and its trailer supply enabled. A properly conducted check finds no supply air at the rear trailer. Which multi-trailer item does the manual direct the driver to check?
Correct answer: The shutoff valves that should pass air through the lead trailer and equipped dolly
Air must pass through the intermediate connections to reach the rear trailer. The manual directs checking the intervening shutoff valves when the rear air-flow check fails; the unused valves at the final end must not be left open for travel.
Source: Georgia DDS Commercial Driver's Study Guide, 2023-2024 cover, retained PDF modified June 16, 2025; Section 7 > 7.4.1 - Additional Air Brake Checks > Check That Air Flows to All Trailers (Double and Triple Trailers); printed 63, physical 63. Current DDS-linked edition reviewed September 13, 2026. ↗
An instructor sees a satisfactory brake response at the first trailer of a double and proposes skipping the rear-of-rig air-flow checks. Which conclusion is sound?
Correct answer: The first trailer's response does not establish that both air circuits reach the rear trailer
A response at the first trailer does not show that the air path continues through the dolly to the rear trailer. The prescribed secured checks cover both supply and service flow at the rear; the service-flow check requires a service application. These checks do not replace the other brake tests.
Source: Georgia DDS Commercial Driver's Study Guide, 2023-2024 cover, retained PDF modified June 16, 2025; Section 7 > 7.4.1 - Additional Air Brake Checks > Check That Air Flows to All Trailers (Double and Triple Trailers); printed 63, physical 63. Current DDS-linked edition reviewed September 13, 2026. ↗
Before bringing a converter dolly under the second trailer, the crew is unsure whether that trailer's brakes will hold. What is the correct response to that uncertainty?
Correct answer: Chock the rear trailer's wheels rather than rely on doubtful brakes
The manual requires the rear trailer to be secured and calls for wheel chocks when there is doubt about its brakes. The dolly or lead vehicle is not a substitute for restraining the rear trailer before coupling contact.
Source: Georgia DDS Commercial Driver's Study Guide, 2023-2024 cover, retained PDF modified June 16, 2025; Section 7 > 7.2.1 - Coupling Twin Trailers > Secure Second (Rear) Trailer; printed 61, physical 61. Current DDS-linked edition reviewed September 13, 2026. ↗
A converter dolly has spring parking brakes. During properly controlled repositioning, which release control does Section 7 specify for this design?
Correct answer: The dolly's parking-brake control
For a spring-brake-equipped dolly, the manual specifies the dolly parking-brake control. The alternate petcock method described for other equipment must not be generalized to this design; maintain the proper restraint and safe setup for the actual unit.
Source: Georgia DDS Commercial Driver's Study Guide, 2023-2024 cover, retained PDF modified June 16, 2025; Section 7 > 7.2.1 - Coupling Twin Trailers > Position Converter Dolly in Front of Second (Rear) Trailer; printed 61, physical 61. Current DDS-linked edition reviewed September 13, 2026. ↗
An empty converter dolly without spring brakes has been withdrawn clear of the rear trailer, and its support is lowered. Which additional restraint does the manual require before it is safely detached from the lead trailer?
Correct answer: Properly placed wheel chocks
For detaching the dolly, the manual calls for converter-gear spring brakes or wheel chocks. In the stated non-spring-brake case, lowered support supplies vertical support but does not replace chocking against rolling.
Source: Georgia DDS Commercial Driver's Study Guide, 2023-2024 cover, retained PDF modified June 16, 2025; Section 7 > 7.2.2 - Uncoupling Twin Trailers > Uncouple Converter Dolly; printed 62, physical 62. Current DDS-linked edition reviewed September 13, 2026. ↗
A fleet assigns a multi-trailer coupling arrangement unlike the common converter-dolly layout in the study guide. What should determine the detailed coupling procedure?
Correct answer: The instructions for that equipment from its manufacturer and/or owner
The manual does not describe every truck-trailer arrangement. It directs drivers to learn the correct procedure for the actual vehicles from manufacturer and/or owner specifications, rather than transfer a familiar sequence to incompatible equipment.
Source: Georgia DDS Commercial Driver's Study Guide, 2023-2024 cover, retained PDF modified June 16, 2025; Section 7 > 7.2.4 - Coupling and Uncoupling Other Combinations; printed 62, physical 62. Current DDS-linked edition reviewed September 13, 2026. ↗
A double is straight on firm, level ground, with brakes applied, required wheels chocked, and the rear trailer properly supported for uncoupling. Before disconnecting dolly air lines, which valves isolate them from the lead unit?
Correct answer: The shutoffs at the rear of the first trailer, and on the dolly if equipped
The twin-trailer uncoupling instructions close the first trailer's rear air shutoffs, and dolly shutoffs if fitted, before disconnecting the dolly lines. The final trailer's terminal valves are not the same isolation point. Follow the full safe procedure for the equipment.
Source: Georgia DDS Commercial Driver's Study Guide, 2023-2024 cover, retained PDF modified June 16, 2025; Section 7 > 7.2.2 - Uncoupling Twin Trailers > Uncouple Rear Trailer; printed 62, physical 62. Current DDS-linked edition reviewed September 13, 2026. ↗
A double is straight on firm, level ground, secured against movement, and prepared for proper rear-trailer uncoupling. How must the rear trailer's landing gear support it before the dolly is withdrawn?
Correct answer: Lower it enough to take some trailer weight off the dolly
The manual lowers the second semitrailer's landing gear enough to remove some weight from the dolly before withdrawal. This is a support condition within the complete procedure, not permission to release the loaded dolly's forward pintle hitch.
Source: Georgia DDS Commercial Driver's Study Guide, 2023-2024 cover, retained PDF modified June 16, 2025; Section 7 > 7.2.2 - Uncoupling Twin Trailers > Uncouple Rear Trailer; printed 62, physical 62. Current DDS-linked edition reviewed September 13, 2026. ↗
