The Caterpillar D9 is a large track-type tractor designed and manufactured by Caterpillar Inc. It is usually sold as a bulldozer equipped with a detachable large blade and a rear ripper attachment.
The D9, with 354 kW (474 hp) of gross power and an operating weight of 49 short tons (44 t), is in the upper end of Caterpillar's track-type tractors, which range in size from the D2 69 kW (92 hp), 9 short tons (8.2 t), to the D11 698 kW (935 hp), 104 short tons (94 t).
A bulldozer or dozer (also called a crawler) is a large tractor equipped with a metal blade at the front for pushing material (soil, sand, snow, rubble, or rock) during construction work. It travels most commonly on continuous tracks, though specialized models riding on large off-road tires are also produced. Its most popular accessory is a ripper, a large hook-like device mounted singly or in multiples in the rear to loosen dense materials.
Bulldozers are used heavily in large and small scale construction, road building, mining and quarrying, on farms, in heavy industry factories, and in military applications in both peace and wartime.
The IDF Caterpillar D9 — nicknamed Doobi (Hebrew: דובי, for teddy bear) — is a Caterpillar D9 armored bulldozer used by the Israel Defense Forces (IDF). It is supplied by Caterpillar Inc. and modified by the Israel Defense Forces, Israeli Military Industries and Israel Aerospace Industries to increase the survivability of the bulldozer in hostile environments and enable it to withstand attack.
In the 1980s the IDF began modifying D9 bulldozers to incorporate armour. The bulldozers can also be fitted with weaponry such as machine guns and grenade launchers. There are various models, including a remote controlled version.
The armoured bulldozer is a basic tool of combat engineering. These combat engineering vehicles combine the earth-moving capabilities of the bulldozer with armour that protects the vehicle and its operator in or near combat. Most are civilian bulldozers modified by the addition of vehicle armour/military equipment, but some are tanks stripped of armament and fitted with a dozer blade. Some tanks (called tankdozers) have bulldozer blades while retaining their armament, but this does not make them armoured bulldozers as such, because combat remains the primary role—earth moving is a secondary task.