Types of Brakes
School buses which are equipped with a hydraulic brake system will have a hand brake lever to the left of the driver (in left hand drive buses) near the floor. It is operated by pushing the lever down with one's hand to apply the brake, and pulling it upwards to release it. However, this has been known to cause severe back problems in drivers who do this regularly, and many choose to push it up with their feet.
Some cars with automatic transmissions are fitted with automatically releasing parking brakes. Later models require the foot brake to be depressed before the car's transmission can be moved from park. When reverse or drive is selected, the parking brake automatically releases. Earlier models would release the parking brake when the gear selector was placed in a forward or reverse gear without requiring any input on the brake pedal at all. These earlier automatic release systems were a safety hazard, since there would be no protection against accidentally knocking the transmission into gear.
In cars with rear drum brakes, the emergency brake cable usually actuates these drums mechanically with much less force than is available through the hydraulic system. In cars with rear disc brakes, the emergency brake either actuates the disc calipers (again, with much less force) or a small drum brake housed within the hub assembly (the inner circumference of the disc is often used instead of a separate drum).
Hudson automobiles used an unusual hybrid hydraulic-mechanical dual-brake system which operated the rear brakes through the otherwise conventional mechanical emergency-brake system when a failure of the hydraulic system allowed the pedal to travel beyond its normal limit.
A number of production vehicles, light and medium duty trucks, and motor homes have been made with a separate drum brake on the transmission output shaft; called a driveline parking brake. This has an advantage of being completely independent of other braking systems. This is effective as long as the drive train is intact — propeller shaft, differential, and axle shafts. In many vehicles, this type of parking brake is operated by either a foot pedal or a hydraulic cylinder controlled by the transmission gear selector, or by both.
Read more about this topic: Parking Brake
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“Science is intimately integrated with the whole social structure and cultural tradition. They mutually support one other—only in certain types of society can science flourish, and conversely without a continuous and healthy development and application of science such a society cannot function properly.”
—Talcott Parsons (1902–1979)
“As for types like my own, obscurely motivated by the conviction that our existence was worthless if we didn’t make a turning point of it, we were assigned to the humanities, to poetry, philosophy, painting—the nursery games of humankind, which had to be left behind when the age of science began. The humanities would be called upon to choose a wallpaper for the crypt, as the end drew near.”
—Saul Bellow (b. 1915)
“There is a limit to the application of democratic methods. You can inquire of all the passengers as to what type of car they like to ride in, but it is impossible to question them as to whether to apply the brakes when the train is at full speed and accident threatens.”
—Leon Trotsky (1879–1940)