Hydraulic brake
During 1904, Frederick George Heath, Redditch, England devised and fitted a hydraulic (water/glycerine) brake system to a cycle using a handlebar lever and piston.
In 1908, Ernest Walter Weight of Bristol, England devised and fitted a four-wheel hydraulic (oil) braking system to a motor car.
He patented it in Great Britain (GB190800241A) in December 1908, later in Europe and the USA and then exhibited it at the 1909 London Motor Show.
The company, which had a factory at Luckwell Lane, Bristol, installed a four-wheel hydraulic braking system on a Metallurgique chassis, fitted with a Hill and Boll body, which was exhibited at the November 1910 London Motor Show.
Although more cars had the brake system installed and the company advertised heavily, it disappeared without achieving the success it deserved.
Knox Motors Company of Springfield, MA was equipping its tractors with hydraulic brakes, beginning in 1915.
[5] The technology was carried forward in automotive use and eventually led to the introduction of the self-energizing hydraulic drum brake system (Edward Bishop Boughton, London England, June 28, 1927) which is still in use today.
Heat generated by this friction is either dissipated through vents and channels in the rotor or is conducted through the pads, which are made of specialized heat-tolerant materials such as kevlar or sintered glass.
(For typical light duty automotive braking systems) In a four-wheel car, the FMVSS Standard 105, 1967;[7] requires that the master cylinder be divided internally into two sections, each of which pressurizes a separate hydraulic circuit.
A master cylinder may also use differing diameters between the two sections to allow for increased fluid volume to one set of caliper pistons or the other and is called a "quick take-up" M/C.
When attached to the low-pressure portion of the throttle body or intake manifold of the engine, the pressure in both chambers of the unit is lowered.
The equilibrium created by the low pressure in both chambers keeps the diaphragm from moving until the brake pedal is depressed.
A relatively small diameter booster unit is required; for a very conservative 50% manifold vacuum, an assisting force of about 1500 N is produced by a 20 cm diaphragm with an area of 0.03 square meters.
This can be caused by either the air valve closing (due to the pedal apply stopping) or if "run out" is reached.
When the piston makes contact with a simple electrical probe in the center of the unit, a circuit is completed, and the operator is warned of a failure in the brake system.
A common upgrade is to replace the standard rubber hoses with a set which are externally reinforced with braided stainless-steel wires.
This makes the power hydraulic system highly suitable for vehicles that must frequently stop and start (such as buses in cities).
The continually circulating fluid also removes problems with freezing parts and collected water vapour that can afflict air systems in cold climates.
Hydraulic braking systems are sometimes subjected to high temperatures during operation, such as when descending steep grades.
The pads which engage the rotating part may become overheated and "glaze over", becoming so smooth and hard that they cannot grip sufficiently to slow the vehicle.
Also, vaporization of the hydraulic fluid under temperature extremes or thermal distortion may cause the linings to change their shape and engage less surface area of the rotating part.
Thermal distortion may also cause permanent changes in the shape of the metal components, resulting in a reduction in braking capability that requires replacement of the affected parts.
