A bobtail truck refers to a semi-truck that doesn’t have an attached trailer to it.
A bobtail truck holds the engine, which provides it with the ability to roll without pulling a trailer behind or a process known as bobtailing.
Origin of the bobtail name
There are two popular theories about where the bobtail origin name came from.
Both theories have to do with animals with shortened tails.
- The first theory refers to the style of the horse's tail cut, which is docked or cut creating a short tail.
- The second theory refers to cats or dogs with short or bobbed tails.
Due to its truncated tail, a bobtail truck looks somewhat similar to these short-tailed animals.
Bobtail and deadheading movements
As I already mentioned, during the bobtailing and deadheading movements drivers and truck owners don't generate any revenue.
Though, the difference is that during "bobtailing" movement the semi-truck rolls without a trailer attached to it while during "deadheading" the tractor pulls a trailer but the trailer is empty.
The danger of bobtailing
On the road, operating a tractor with a trailer attached to it is safer than operating a bobtail.
If you don't have experience bobtailing, you may not know what are the dangers of operating a bobtail truck.
Here are some main characteristics of a bobtail truck:
- Front wheel weight
Most of the braking power is moved to the front wheels. However, this front wheel axle is designed for steering rather than braking.
- Designed to haul heavy trailers
Initially, semi-trucks were designed to carry heavy trailers. In this configuration, they have the most balance.
Here are some of the main dangers of bobtailing:
- Difficult to maneuver
Just like any other truck, a bobtail truck can be difficult to maneuver, do some aggressive maneuvers, or maneuver during slippery roads because this behavior may spin the tractor off control causing accidents.
- Pick up high speed faster
Due to its lighter weight and stronger engine, a bobtail truck can quickly pick up more speed than a loaded truck, which may increase the risk of an accident.
- Difficult to stop bobtail
Because the steer axle is front-heavy, bobtail tractors become unbalanced. Because of that, the rear axle doesn't provide much braking power and it can take the truck a long time to stop.
- Don't slam the brakes
When bobtailing, don't slam on the brakes.
Consider that the semi-truck's braking system is located on the rear wheels.
When the driver brakes hard, the rear wheels seize, and the semi-truck pivots around around the front wheels.
- The danger when driving in the rain
As such, bobtail trucks are more susceptible to skidding in sudden turns or tight curves, especially if it’s raining.
Bobtailing is extremely hazardous on snowy or wet roads because the frictional force between the tires and the road decreases significantly.
To avoid accidents while bobtailing, a significant space between the semi-truck and other vehicles is imperative.
What is a bobtail used for?
The configuration of bobtail trucks can’t transport any type of cargo.
Bobtail is what a semi-truck is called in between trips when the truck drops off a trailer and goes to pick up a new one.
In that short duration in between dropping off the old trailer and picking up the replacement, the truck is called a bobtail tractor.
Mainly, when the truck driver is bobtailing, he is not making money. He can use the Personal
Conveyance to do some personal things like go grab some food, for example.
That is why some people ask if you need a CDL to drive a semi for personal use.
Bobtail truck dimensions
The bobtail truck dimensions are:
- Length - 24 feet long.
- Height - 13’4 tall.
- Width - 96” wide, excluding the mirrors.
The weight with two drivers and full fuel and DEF tanks is:
- Weight - up to 20,000 pounds
Typically the weight of a bobtail truck is spread over 10,000 lbs on the steer axle and 8,500–9,000 lbs on the drive axles altogether.
The weight of the bobtail truck depends on the size of the sleeper cab and its specs.
Types of bobtail trucks
There are three common types of Bobtail trucks.
1.Semi-Truck or Running Bobtail Truck:
Most often, the semi-truck without a trailer attached is a bobtail.
2. Small bobtail trucks:
The second type of bobtail truck is one in which every axle on the truck is attached to the same chassis. These are typically small- to medium-sized trucks, such as a bobtail delivery truck or a bobtail dump truck. In some cases, you don’t even need a special license to drive this kind of bobtail truck.
3. Straight Propane Truck:
Another type of bobtail truck refers to straight propane trucks.
These straight propane tank trucks fit a specially-designed tank on the rear bed of the truck.
These rounded shape tanks can maintain adequate pressure and temperature during the ride and have a storage capacity of about 5000 gallons of LPG (Liquefied petroleum gas). Also, they use an attached hose to deliver the gas from the bobtail’s tank to the customer’s.
These types of trucks are significant contributors to supplying propane or gasoline to fuel stations and auto dealers.