Frequently Asked Questions
What is the cost of service?
Although there is no standard cost when it comes to servicing transmissions, the vast majority of complete transmission “servicing” averages below $200.
How long does a typical transmission repair take?
24-48 Hours is the average turn-over time overhaul work - some issues being resolved in minutes - loose hoses - lines - etc...
How often should a transmission be serviced?
Each case should be assessed on its merits, which include driving conditions, make and model. Harder working vehicles should have the transmission serviced regularly, 15-20,000 miles. Transmissions with synthetic oil can extend this period.
What are the elements or processes of a transmission service?
Due to the variety of makes and models this can vary from one transmission to the next, however the standard sort of process includes the removal and washing of the transmission, during which the filter is replaced, gaskets replaced and any required adjustments are made. The transmission unit is then filled with fresh oil, tested and inspected for leaks. Regular servicing and maintenance of your transmission and attention can prolong the useful life.
Why did my automatic transmission fail?
There are a number of possible reasons for automatic transmission failure, however overheating is considered to be the primary cause, due to the engine’s cooling system failing or faulty connections in the system leading to complete or partial erosion of the clutch system.
What is an automatic transmission and how does it work?
"automatic transmission, arrangement of gears, brakes, clutches, a fluid drive, and governing devices that automatically changes the speed ratio between the engine and the wheels of an automobile. Since its introduction in 1939, the fully automatic transmission has become optional or standard equipment on most passenger cars. When the transmission is in the drive position, the driver has only to depress the accelerator pedal, and as the car gathers speed the transmission will shift automatically through its entire forward range• of gears from low to high (ratios of the speeds of drive shaft and engine shaft) until the two shafts are directly connected through the oil in the fluid drive, which may be either a two-element fluid coupling or a three-element torque converter. When the car loses speed the transmission automatically shifts back from high to low gear.
A fluid coupling has two vaned turbines facing each other. As the engine-driven turbine turns, a torque is transmitted by churning oil that circulates between them. (This is much like two fans facing each other; as the one is turned on and as its speed accelerates, the air flowing from it will cause the other fan to turn.) In the automobile, the oil permits the fluid coupling to slip easily at low engine speeds (thus also permitting idling while the brake is on). At high speeds the slippage is almost eliminated, and the fluid coupling functions like a solid connection.
The hydraulic torque converter resembles the fluid coupling. Oil transmits power in both. At lower speeds the blades of a pump, or impeller, force oil against the blades of a stator. These blades deflect the oil against a turbine, therefore increasing torque. At higher speeds, as in the case of fluid coupling, the oil, stator, pump, and turbine turn together as a unit. The oil moves in different directions in different parts of a hydraulic torque converter. The pump spins and throws the oil outward. The doughnut-shaped housing that encloses the pump and turbine forces the oil toward the turbine. There it strikes the turbine blades and slides inward toward the turbine hub and then returns back through the stator. The stator is equipped with an overrunning, or oneway, clutch. This device permits the stator to be used for deflection of oil at low speeds and to move with the pump and turbine at high speeds. What is described here is the simplest system; frequently the system has more elements to deflect and direct the oil, and often a torque converter is combined with gear transmissions.
All shifting is done by a combination of planetary gears and a speed-sensitive governing device that changes the position of valves that control the flow of hydraulic fluid."
Source:
The New Encyclopaedia Britannica, 15th Edition.
The New Encyclopaedia Britannica, 15th Edition.
transmission, in mechanical engineering, a device interposed between a source of power and a specific application for the purpose of adapting one to the other. Most mechanical transmissions function as rotary speed changers; the ratio of the output speed to the input speed may be constant (as in a gearbox) or variable. On variable-speed transmissions the speeds may be variable in discrete steps (as on an automobile or some machine-tool drives) or they may be continuously variable within a range. Step-variable transmissions, with some slip, usually employ either gears or chains and provide fixed speed ratios with no slip; stepless transmissions use belts, chains, or rolling-contact bodies.
A widely used and inexpensive stepless drive consists of a V-belt running on variable diameter pulleys. The sides of the pulleys are conical on the inside to match the taper of the V-belt, and moving them closer together causes the V-belt to move outward from the center of the pulley and operate on a larger effective circle; this movement changes the speed ratio. Such drives depend on friction and are subject to slip. Stepless transmissions employing rolling-contact bodies are known as traction drives. In these transmissions, power is transmitted in a variety of ways that depend on the rolling friction of bodies in the form of cylinders, cones, balls, rollers, and disks.
For some applications transmissions are designed so that as the applied torque (turning moment) increases, the contact pressure between the bodies increases so that slippage is reduced. A special traction lubricant that stiffens as the load is applied may be used to increase the tractive effort. Traction transmissions are used in applications where quietness is important.
Source:
The New Encyclopaedia Britannica, 15th Edition.
The New Encyclopaedia Britannica, 15th Edition.
What is a differential gear, in automotive mechanics, gear arrangement that permits power from the engine to be transmitted to a pair of driving wheels, dividing the force equally between them but permitting them to follow paths of different lengths, as when turning a corner or traversing an uneven road. On a straight road the wheels rotate at the same speed; when turning a corner the outside wheel has farther to go and will turn faster than the inner wheel if unrestrained.
The conventional automobile differential was invented in 1827 by a Frenchman, Onesiphore Pecqueur. It was used first on steam-driven vehicles and was a well-known device when internal-combustion engines appeared at the end of the 19th century.
The power from the transmission is delivered to the bevel ring gear by the drive-shaft pinion, both of which are held in bearingsin the rear-axle housing. The case is an open boxlike structure that is bolted to the ring gear and contains bearings to support one or two pairs of diametrically opposite differential bevel pinions. Each wheel axle is attached to a differential side gear, which meshes with the differential pinions. On a straight road the wheels and the side gears rotate at the same speed, there is no relative motion between the differential side gears and pinions, and they all rotate as a unit with the case and ring gear. lfthe vehicle turns to the left, the right-hand wheel will be forced to rotate faster than the left-hand wheel, and the side gears and the pinions will rotate relative to one another. The ring gear rotates at a speed that is equal to the mean speed of the left and right wheels. If the wheels are jacked up with the transmission in neutral and one wheel is turned, the other wheel will turn in the opposite direction at the same speed.
The torque (turning moment) transmitted to the two wheels with the Pecqueur differential is the same. Consequently, if one wheel slips, as in ice or mud, the torque to the other wheel is reduced. This disadvantage can be overcome somewhat by the use of a limited-slip differential. In one version a clutch connects one of the axles and the ring gear. When one wheel encounters low traction, its tendency to spin is resisted by the clutch, thus providing greater torque for the other wheel.
Source:
The New Encyclopaedia Britannica, 15th Edition.
The New Encyclopaedia Britannica, 15th Edition.
