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Ursus 55 [1939]


Ursus 55 [1939]


Ursus 55 is a Two-stroke hot-bulb engine crawler tractor.


Crawler tractor features:

  • Weight: 5200 kg;
  • Fuel: Oil or Diesel;
  • Power: Flywheel Pulley: 55 CV
    Tow Bar: 40 CV
  • Max Speed:
    1° gear 2.750 km/h;
    2° gear 3.750 km/h;
    3° gear 4.750 km/h;
    4° gear 6.250 km/h;
    R  gear 3.900 km/h.


Two-stroke hot-bulb engine features:

The hot-bulb engine has one piston, inside a cylinder, connected to two big flywheel by a connecting rod and crankshaft. The flow of gases through the engine is controlled by the piston covering and uncovering ports in the cylinder wall in two-strokes.
In the hot bulb engine, combustion takes place in a separated combustion chamber, the "vaporizer" (also called the "hot bulb"), mounted on the cylinder head, into which fuel is sprayed. It is connected to the cylinder by a narrow passage and is heated by combustion gases while running; an external flame, such as a blow torch or slow-burning wick, is used for starting.

The pre-heating time depends on the engine design, the type of heating used and the ambient temperature, but for most engines in a temperate climate generally ranges from 2—5 minutes to as much as half an hour if operating in extreme cold or the engine is especially large. The engine is then turned over, usually by hand, but sometimes by compressed air or an electric motor.

Once the engine is running, the heat of compression and ignition maintains the hot bulb at the necessary temperature, and the blow-lamp or other heat source can be removed.

The fact that the engine can be left unattended for long periods while running made hot-bulb engines a popular choice for applications requiring a steady power output, such as farm tractors, generators, pumps and canal boat propulsion.

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