CHAPTER 9 - FRONT-END LOADERS, EXCAVATORS, AND DITCHERS

Front-end loaders, excavators, and ditchers are used to support construction operations anytime there is a need to lift, load, unload, clear, grub, excavate, or trench. A variety of makes and models of this equipment are used in 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. his chapter covers the general characteristics and basic principles of operations of front-end loaders, excavators, and ditchers.

FRONT-END LOADERS

The front-end loader is a self-contained unit mounted on rubber tires or tracks and is one of the most versatile and capable pieces of equipment used in the NCF. The front-end loader can be equipped to operate as a loader, a dozer, a scraper, a clamshell, a forklift, a backhoe, a crane, an auger, or a sweeper.

RUBBER-TIRED FRONT-END LOADER

Mounted on large rubber tires, the front-end loader has a relatively low ground bearing pressure (approximately 45 pounds) that enables it to perform a large variety of jobs. The rubber-tired front-end loader (fig. 9-1) has three manually selected forward gear ranges that permits good mobility when traveling from one jobsite to another. The full power soft shift transmission allows the gear range and direction of travel changed at anytime without stopping the machine from maintaining a high rate of production. The large rubber tires provide good traction on unstable surfaces and allow the front-end loader to perform on side slopes of 15 percent and on front slopes up to 30 percent. The hydraulic system gives the operator positive control of the front-end loader attachments and steering system.

CRAWLER-MOUNTED FRONT-END LOADER

Mounted on crawler tracks, the crawler-mounted front-end loader has a low ground bearing pressure that

Figure ^{9-1 .} -Rubber-tired front-end loader.

enables it to operate in areas where wheeled frontend loaders cannot go. The crawler-mounted frontend loader (fig. 9-2) has a lower speed than a rubber-tired front-end loader, and this decreases its mobility; however, the crawler-mounted frontend loader can be operated on side slopes of up to 35 percent and on front slopes of up to 60 percent. The hydraulic system provides positive control of the front-end loader, and the crawler tracks are normally semi-grouser shoes (fig. 9-3) that permit it to work on firm ground with little damage to the surface.

ATTACHMENTS

Attachments contribute to the efficient performance of front-end loaders. Some loaders used in the NCF are procured with a bucket, forklift, and backhoe attachments (fig. 9-4). These attachments allow the front-end

Figure 9-2.-Crawler-mounted front-end loader.

Figure 9-3.-Semi-grouser shoe.

Figure _9-4.-Front-end loader attachments.

Figure 9-5.-Attachment connection.

loader to be an ideal piece of equipment for construction projects, saving the need for numerous pieces of equipment that can be used elsewhere.

Quick-disconnect hydraulic hose fittings and hydraulic controlled locking pins permit these attachments to be changed easily, as shown in figure 9-5.