Classification of bulldozers:
Based on the purpose of use:
- General purpose
- Special purpose (pushers, underground bulldozers, underwater bulldozers);
Based on a torque category:
- Small size
- Medium size
- Super heavy.
Based on a blade control system:
Modern bulldozers are equipped with hydraulic control system.
Based on a work tool construction:
- Equipped with a fixed blade which is perpendicular to the axial axis of a basic vehicle;
- Equipped with a turning blade which can be set up to the angle of 53° in both sides to the axial axis of the vehicle.
To buy a used bulldozer you have to decide what kind of works the vehicle will have to carry out and what service conditions will be. It is very important because these features determine parameters of the vehicle.
Main components of bulldozers
A blade. There are 6 types:
- straight turning blade
- straight fixed blade
- Spherical blade
- Spherical blade for bulk materials
- Equipped with a pusher
Chassis. Construction and balance of chassis determines smoothness of movement. Parameters of crawler bulldozers chassis: suspension, number of links in the chain, number of basic and supporting rollers, number of gear segments, standard and optional tracks.
Transmission. It is responsible for changing movement direction and shifting gears. It also provides a movement speed in a preset range. The main characteristic is maximal torque, kW. Consists of a steering gear, a service and parking brakes, a final reduction gear, cleaning and cooling systems.
An engine. In most cases diesel engines are used. Main engine characteristics are the following: power, capacity, rated engine speed and the type of cooling. Also, bulldozer’s engine has to meet the emission requirements.
Control system. It is located in the driver’s cab. Up-to-date control systems consist of microcomputers.
The control system consists of several joysticks.
CAT, Liebherr, Komatsu, and others are the most popular bulldozer manufacturers. Each of these companies is instantly improving its vehicles and putting innovative technologies into effect. Besides technical and performance characteristics, much attention is paid to driver’s comfort and security.
Special features of some bulldozers
Liebherr PR 724 is a vehicle equipped with a 6-positions blade with the working volume of 3,14 – 4,27 m3, engine power 120 kW / 163 hp, hydrostatic transmission with electronic control system. Komatsu D155A-5 has the power of 225 kW / 302 hp and 4,9 – 11,8 m3 of blade volume, hydro-mechanic transmission. Caterpillar D6 by CAT is equipped with a 136 kW engine, this model can be used under weather conditions from -50 to +50, as well as in severe swampy terrain).
Before you buy a bulldozer, you have to pay attention to the level of vehicle’s main components wear, for instance engine, chassis, fuel system, control system, frame and blade. Knocking noises in engine and adjacent components point on the malfunctions. Attachments are also to be checked as well as adjusting bolts bracers, cables, side rails on supporting pins, frame stands, blade fixtures to pins and beams. When block-and-tackle system is used, you should also make sure that all cables are intact and there are no knots. Lubrication system and cooling system have to be examined carefully as well, lubrication is realized only according to the lubrication chart.
Special requirements have to be met concerning anti-freeze liquids and oils when the weather is cold. The parameters must correspond to the temperature regime. Non-observance of these requirements can lead to a short life of the key parts of the vehicle and emergency conditions. After operation under harsh weather conditions freezing on main vehicle’s components is possible, what should also be checked carefully and eliminated at short notice.