October 18th, 2011
Brakes are considered to be the second important and most essenstial system required in all automobiles either it’s a gasoline engine, diesel engine, hybrid or electric car. For agricultural use, the tractor is to be considered as powerful or most useful automobiles that are especially designed for only these purposes. Two big wheels without any suspension and the exhasut pipe located at the upper side from the engine and trailors located behind are the key feature of tractors which makes it perfect for use as agriculture purposes.
Now we come to the point on the most essential system: the braking system. This system has most frequent use during the whole life.
Older tractors are equipped with the mechanical drum brake system. As tractors are used for the agriculture works and it is required for the instance or frequent stopping with minimum stopping distance for seeding and croping purposes engineers are in search of the brakes that fulfils all requirements listed above. And the time came when mechanical drum brake has been replaced by hydraulic brake that are used now a days by the leading tractor manufacturers like mahindra, sonalika, punjab, eicher, escort, john deere and many other in their all latest tractor models.
Tractor hydraulic braking system consists of reservoir, brake control valve, release connector, brake cylinder, brake shoes, master cylinder and linkages.
Hydralic brake works on the principal of great french mathematicians “Blaise Pascal”. It states that “Pressure exerted in a mass of confined incompressible liquid is transmitted throughout the liquid with same magnitude in all directions”.
In a construction of braking mechanism, foot pedal of brale is connected to the brake master cylinder through the linkage. Master cylinder is full with brake fluid which is operated by foot pedal via brake control valve. Again master cylinder is connected to the wheel cylinder through the fluid line inside the brake drum mechanism. When we look inside the brake drum mechanism, it consists of brake shoe, cam, brake liner and rotating drum on which wheels are mounted.
Hydraulic braking system layout during Brake in applied postion
In working, when driver presses the brake pedal, it pushes the piston in a forward direction inside the brake master cylinder and force on to the fluid to send it to the wheel cylinder inside the brake drum. Again, wheel cylinder consists of piston-cylinder assembly. Liquid coming from the master cylinder, forces the piston in outward direction. Wheel cylinder piston end is connected to the brake shoe. When piston goes outward, shoes also slides in an outward direction towards the rotation of drum and stops it with the help of friction pad mounted inside it and thus brake is applied and tractor stops.
Hydraulic braking system layout during Brake in release postion
Inside the brake drum both the brake shoes are connected to the return springat the centre and fixes at the end. In a return mechanism, when driver removes the foot from the brake pedal, return spring inside the drum take both the shoes to its original position and again drum starts rotation which rotates wheels and thereby tractor.
John is an enthusiastic automotive writer. He shares his knowledge in different aspects of auto systems like braking system, cooling system, air conditioning system etc…He has published various papers on ford brake pads replacement.