CHAPTER 11 DOZERS AND ROLLERS

The dozer, technically known as a crawler tractor, is used as follows: as a prime mover for pushing or pulling loads, as a power unit for winch operations, or as a dozer for earthwork operations and demolition work. Rollers are compaction equipment used to achieve mechanical compaction of earthwork materials required by project specifications.

A variety of makes and models of dozers and rollers are used by the Navy and the Naval Construction Force (NCF). Each operator is responsible for reading the operator's manual to obtain detailed information about each make and model. This chapter covers the general characteristics and basic principles of dozer and roller operations.

DOZERS

The dozer, commonly called a bulldozer, is a crawler tractor on which a dozer blade has been mounted (fig. 11- 1). Dozers are usually rated by size and power. The pull developed at the drawbar is expressed in pounds or as drawbar horsepower. The drawbar pull is greatest in the lowest transmission gear range. Although the specifications for dozers may vary among different manufacturers, the maximum speeds are seldom in excess of 8 mph.

The dozer is equipped with a diesel engine and is supported on the ground by a track assembly. The track assembly provides all-type-terrain versatility due to the low ground bearing pressure at the track. This lower ground bearing pressure, varying from 6 to 9 pounds per square inch, has a distinct flotation advantage over rubber-tired equipment ground bearing pressure that varies from 25 to 35 pounds per square inch. Dozers are capable of operating efficient y in muck or water as deep as the height of the track for short periods of time. When the dozer is properly waterproofed, it can operate in fairly deep water.

CAUTION

When working in water that is deep enough to reach the radiator, be sure to disconnect the fan belt. If the fan blades hit the water while under power, the y could bend or break off, possibly causing damage to the radiator. Additionally, exercise extreme caution to ensure the engine does not overheat when the fan or water pump belts are disconnected.

Figure 11-1.-Dozer.

Figure 11-2.-Side view of crawler tractor chassis.

Dozers can move from jobsite to jobsite under their own power at slow speeds; however, this is a poor practice and tends to shorten the operational life of the dozer. For this reason, dozers should be transported by tractor-trailer from jobsite to jobsite.