Georgia CDL Tanker Test key terms

The forward and backward movement of liquid inside a partly filled tank when the vehicle changes speed. It pushes against the tank ends and can shove the whole vehicle, so smooth acceleration and braking are essential.

The empty space above the liquid in a tank that is not completely full. The larger this space, the more freely the contents can slosh, increasing surge forces on the vehicle.

The measured empty volume left at the top of a tank after filling, expressed as a percentage of total tank capacity. It allows for liquid expansion and is set by the shipper or regulations.

An internal wall inside a tank that divides the liquid into smaller compartments. Baffles slow the movement of liquid from one end of the tank to the other and reduce surge forces.

A solid internal partition that seals one tank compartment from another. Unlike a baffle with openings, a bulkhead keeps liquids in separate sections so they cannot mix or flow together.

A tank trailer divided into several separate sections, each filled and unloaded independently. Load distribution across compartments affects axle weight and stability, so the driver must know the fill plan.

Applying the brakes gradually and steadily rather than abruptly. In a tank vehicle, gentle brake pressure limits liquid surge and reduces the chance of a jackknife or loss of control.

The total distance a vehicle travels from the moment the driver perceives a hazard until it comes to a complete stop. Fully loaded tank vehicles need much more room than lighter vehicles.

The gap kept between your vehicle and the one ahead. Tank vehicles should leave extra room because surge and heavy weight make sudden stops difficult and slow.

The point where the weight of the vehicle and its load is balanced. A high center of gravity, common in tank vehicles, makes the rig easier to tip over in turns.

A crash in which the vehicle tips onto its side or roof. Tank vehicles are prone to rollover because of their high center of gravity and the shifting weight of liquid loads.

The maximum safe speed for taking a curve without losing control or tipping. It is usually well below the posted limit for tank vehicles and must be judged before entering the curve.

The outward push felt by a vehicle turning a corner, caused by its momentum. In a tank vehicle this force combines with liquid surge and can lift wheels or tip the trailer.

The side-to-side or front-to-back movement of liquid inside a tank as the vehicle turns, climbs, or stops. It changes weight on each axle and wheel and can upset stability.

The total load carried by one axle and its tires. Tank loads must be spread so no axle is overloaded, since excess weight reduces braking and steering control.

The way total vehicle weight is spread among axles and tires. Correct distribution keeps steering tires loaded, prevents axle overload, and helps the vehicle handle predictably.

The written arrangement showing which compartments are filled and with what product before a trip. It lets the driver check weight limits and confirm the load is balanced.

The systematic check of the vehicle before driving, covering brakes, tires, lights, tank fittings, and leaks. It is required by regulation and is the driver's main defense against equipment failure.

A complete circuit of the vehicle on foot, checking each side, the front, the rear, and the underside. It is the practical method for performing the required pre-trip inspection.

Looking, smelling, and feeling for escaping product around valves, hoses, gaskets, and the tank shell. Any leak must be fixed before the vehicle moves.

A quick way to stop the flow of product, such as closing the internal valve or using the remote shutoff. Knowing its location and operation is part of pre-trip readiness.

A valve mounted inside the tank outlet that stops product flow if the external piping is damaged. It is a key safety device on cargo tank vehicles and must be checked before driving.

A tank fitted with internal partitions that break up liquid movement. It reduces surge but does not eliminate it, so the driver still must accelerate and brake gently.

Filling a tank from the top so product falls through the space above the liquid. It can create static electricity and vapors, so many operations require bottom loading instead.

A system that captures fuel vapors displaced during loading and returns them to storage. It prevents vapor release and reduces fire risk during tank filling.

A loss of control in which the tractor and trailer fold toward each other at an angle. Hard braking on slick pavement with a tank load makes this more likely.

Loss of traction in which tires slide instead of rolling. Tank vehicles skid more easily when liquid shifts weight off the drive tires or when brakes are applied too hard.

An electronic system that prevents wheels from locking during hard braking. It helps maintain steering control but does not shorten stopping distance on all surfaces or replace safe following distance.

The loss of braking power when brakes overheat, common on long downgrades with a heavy load. Using a lower gear and engine braking helps prevent it.

Using a lower gear so the engine slows the vehicle instead of relying only on the brakes. It is the preferred method for controlling speed on long downgrades with a tank load.

The controlled pace maintained when descending a hill, chosen before the grade begins. Excess speed on a downgrade with liquid surge can overwhelm the brakes and lead to a runaway.

The outer wall of the tank that holds the product. Cracks, dents, or corrosion in the shell are grounds to keep the vehicle out of service until repaired.

The lid that seals the top opening of a tank compartment. It must be closed and tight before driving, or product can spill and vapors can escape.

The force created when moving liquid hits the front or rear of the tank. It can be strong enough to push a truck forward at a stop or shove it into an intersection.

The delay between seeing a hazard and pressing the brake. With heavy tank loads, that delay translates into a long distance traveled before slowing even begins.

A problem serious enough that regulations forbid driving the vehicle until it is repaired. Leaking tank fittings and bad brakes are examples a driver must catch in pre-trip.