8.2 – Driving Tank Vehicles

Hauling liquids in tanks requires special skills because of:

• All these are correct
• The movement of the liquid
• The high center of gravity
• How easily they can roll over

Describe unbaffled liquid tankers:

• They are sometimes called “rodding” tanks and they have mastheads inside to prevent the liquid from sloshing side to side
• They are sometimes called “smooth bore” tanks and they have nothing inside to slow down the flow of the liquid. Therefore, the forward-and-back surge is very strong.
• They are sometimes called “masthead” tanks and they have wires inside to slow down the flow of the liquid from side to side.
• They are sometimes called “lockhead” tanks and they have completely separate tanks within the main tank to divide up the liquid

The amount of liquid that can be loaded into a tank depends on:

• Legal weight limits
• The weight of the liquid.
• The amount the liquid will expand in transit.
• All these are correct

Never load a cargo tank totally full. Liquids expand as they warm and you must leave room for the expanding liquid. What is this extra room called?

• Seepage
• Drainage
• Compartmentalization
• Outage

What type of product do unbaffled tankers normally haul, and why?

• They transport gasoline because they need to divide the tank into separate compartments for the different grades of gasoline
• They transport chemicals because of the special anti-corrosive properties of the unbaffled tanks
• They transport chemicals to prevent the sloshing of the liquid from side to side
• They transport food products (e.g., milk) because sanitation regulations forbid the use of baffles because of the difficulty in cleaning the inside of the tank.

High center of gravity means:

• Sloshing will decrease the height above the road that the weight of the liquid is centered
• Gravity will center its influence on the liquid closest to the frame of the tractor
• Much of the load's weight is carried high up off the road. This makes the vehicle top-heavy and easy to roll over.
• That much of the load's weight is carried low down near the road. This makes the vehicle top-heavy and easy to roll over.

Liquid surge results from the movement of the liquid in partially filled tanks. What are some characteristics of liquid surge?

• If the truck is on a slippery surface such as ice, the wave can shove a stopped truck out into an intersection
• When the wave hits the end of the tank, it pushes the truck in the direction the wave is moving.
• All these are correct
• When coming to a stop, the liquid will surge back and forth

Some liquid tanks have bulkheads in them with holes that let the liquid flow through. What are these called, and what do they do?

• None of these are correct
• They are called baffles and they help to control the forward and backward liquid surge.
• They are called mastheads and they help prevent the sides of the tank from getting crushed inward
• They are called centuries and they help prevent pressure from building up in the tank

Liquid surge results from:

• The tanker being overloaded on the trailer axles
• The tanker being overloaded on the drive axles
• The movement of the liquid in a tank that is completely full
• The movement of the liquid in partially filled tanks.

What have tests shown about tankers, and how should you manage it?

• Tankers will be more likely to turn over if the center of gravity is low. Keep the center of gravity high when loading a tanker.
• Tankers will not turn over if you follow the posted speed limit signs in curves. Always stay at the posted speed limit for any curve
• Tankers can turn over at the speed limits posted for curves. Take highway curves and on-ramp/off-ramp curves well below the posted speeds.
• Stopping distance will decrease as the liquid sloshes forward. Press the brakes with more of a "stabbing" motion to quickly slow the vehicle.

Complete!

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