This endorsement is required if the driver will pull two or three trailers. To receive this endorsement, applicants must pass a..

This endorsement is required if the driver will pull two or three trailers. To receive this endorsement, applicants must pass a test. The test consists of 20 multiple choice questions. To pass, the applicant must answer at least 16 questions correctly. Test questions come from the Ohio Commercial Driver’s License Manual. Questions come from chapters covering: Driving Safely, Air Brakes (if applicable), Combination Vehicles and Doubles and Triples. The Double/Triple endorsement can be used with the Class A CDL.

Passing grade:

A tread depth of ____ should be in every major groove of a front tire.

For safe operation, a commercial motor vehicle needs a tread depth of 4/32 of an inch in every major groove on the front tires, and a tread depth of 2/32 of an inch on other tires.

Why do large vehicles use air brakes?

If used and maintained properly, air brakes are a safe and effective way to stop large, heavy vehicles.

How can you check for a leak in hydraulic brakes?

Check hydraulic brakes by pumping the brake pedal three times before applying firm pressure to the pedal for five seconds. The pedal should not move. If it does, there may be a leak or some other problem in the braking system.

Texting while driving is especially dangerous because:

Texting while driving is particularly dangerous because it is both a mental and physical distraction to the driver. In addition to diverting a driver's mental attention away from the road, texting requires a person to remove at least one hand from the vehicle's controls.

While driving, a driver should:

It is essential that you are aware of what is happening on all sides of your vehicle at all times. Scan the road ahead and make regular checks of the mirrors on both sides of your vehicle while you are driving.

Vehicles with low underneath clearance may be difficult to drive:

Railroad-highway crossings may be difficult to cross when pulling a trailer with a low underneath clearance. In particular, both low-slung units and single-axle tractors pulling long trailers are especially challenging to drive over raised crossings.

Glad hands should be securely connected to:

When inspecting the convertor dolly, ensure that all components are present and in proper working condition. The air lines should be securely attached to the proper glad hands and should not contain any leaks. They should be attached with enough slack to allow easy turning.
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