Crawler Dozer with a Rear Ripper

About this drawing

A crawler bulldozer with ripper carries two main tools: the front blade for pushing dirt and the ripper, a big claw on the back. When the ground is too hard or rocky to push, the operator sinks the ripper in and drives forward to break it apart, then turns around and clears the loosened chunks with the blade.

The machine grew out of crawler tractors from the early 1900s, designed so heavy farm equipment would not sink into soft California fields. In the 1920s, builders started bolting blades on the front to move earth, and the bulldozer was born. During World War II, crews used them to carve roads and airstrips in remote places at amazing speed.

Today dozers work in mines, highways, dams and landfills. Modern cabs protect the operator in a rollover, and many machines use satellite guidance that shows exactly how much soil to cut so the ground ends up at the right slope.

All that power comes at a cost: a dozer burns a lot of fuel and wears down its tracks, so it needs constant care. Mechanics check the track links, rollers and hydraulic oil so the machine can keep working for thousands of hours.

• bulldozer
• crawler tractor
• heavy equipment
• construction
• ripper