A serpentine belt (or drive belt [1] ) is a single, continuous belt used to drive multiple peripheral devices in an automotive engine, such as an alternator, power steering pump, water pump, air conditioning compressor, air pump, etc. [2] The belt may also be guided by an idler pulley and/or a belt tensioner (which may be spring-loaded, hydraulic, or manual).
To allow the belt to pass over more than three pulleys with a large enough wrap angle to avoid slipping, idler pulleys which press against the back of the belt are included, forcing the belt into a serpentine shape. To accommodate this bidirectional flexing while remaining strong enough to transfer the total force required by multiple loads, a serpentine belt is almost always of multi-groove (multi-vee, poly-v, or multi-rib) construction.
On some engine designs, the "back" (smooth side) of the belt may drive some accessories. This is typically limited to components requiring less torque or where a large angle of wrap is present. Such accessories will counter-rotate vs. the "normal" pulleys. Some vehicles use two serpentine belts for their system, such as the manual transaxle equipped Ford Taurus SHO, 1995–1999 DOHC Nissan Maxima, vehicles using the supercharged GM 3800 engine, [3] [4] and many BMWs.
It is more efficient than the older multiple belt system and may consume less space in the engine compartment. By using a single, wider belt instead of multiple, thinner belts, the belt may be put under increased tension without stretching. Higher tension reduces slip, which increases belt life and mechanical efficiency. Reduced slip can allow the use of lower-ratio pulleys; this reduces the load on the engine, increasing fuel economy and available power. The tendency for V-belts to "flip over" in the pulley groove (at high RPM and/or when the belt stretches) is eliminated, and a serpentine belt is also much easier to maintain and replace, since there is no need to remove multiple belts in order to replace one of them, although newer adjustable-length V-belts ("link belts") can be put on without having to remove other belts, and their link design also allows a self-tensioning characteristic to reduce the risk of flipping over. Also since only one movable belt tensioner is required all of the peripheral components (alternator, A/C compressor, etc.) can simply be mounted to the engine without the need to swivel.
The drawback of this single belt is that if the belt breaks or is knocked loose, the vehicle instantly loses multiple critical functions. The water pump, power steering pump, and alternator (for battery charging) would cease functioning. The vehicle becomes quickly unusable due to loss of engine cooling. [2] The belt typically gives ample visual warning of impending failure, sometimes even totally shedding several grooves (ribs) while continuing to function acceptably.
Furthermore, the loss of function of a single component (such as a power steering pump or air conditioning compressor) causes the failure of the entire accessory drive. Sometimes, this can be overcome with a shorter belt to bypass the failed components (if the belt is available). But this is not always possible. Thus, it is possible to be stranded because of, say, a seized power steering pump or A/C compressor clutch. It may also not be possible to restore use of the vehicle without first repairing the bad power steering pump or A/C compressor, which precludes a simple roadside repair.
The Buick Electra is a full-size luxury car manufactured and marketed by Buick from 1959 to 1990, over six generations. Introduced as the replacement for the Roadmaster lines, the Electra served as the flagship Buick sedan line through its entire production and was offered as a six-passenger four-door sedan with two-door sedan, two-door convertible, and five-door station wagon variants.
A continuously variable transmission (CVT) is an automated transmission that can change through a continuous range of gear ratios. This contrasts with other transmissions that provide a limited number of gear ratios in fixed steps. The flexibility of a CVT with suitable control may allow the engine to operate at a constant angular velocity while the vehicle moves at varying speeds.
A fan clutch is a thermostatic engine cooling fan that can freewheel at low temperatures when cooling is not needed, allowing the engine to warm up faster, relieving unnecessary load on the engine. As temperatures increase, the clutch engages so that the fan is driven by engine power and moves air to cool the engine.
In a piston engine, either a timing belt or timing chain or set of timing gears is a perishable component used to synchronize the rotation of the crankshaft and the camshaft. This synchronisation ensures that the engine's valves open and close at the correct times in relation to the position of the pistons.
The Buick LaCrosse is a four-door, front-wheel-drive sedan manufactured by Buick since model year 2005, and marketed variously across four generations for the North American and Chinese markets.
The Iron Duke engine is a 151 cu in (2.5 L) straight-4 piston engine built by the Pontiac Motor Division of General Motors from 1977 until 1993. Originally developed as Pontiac's new economy car engine, it was used in a wide variety of vehicles across GM's lineup in the 1980s as well as supplied to American Motors Corporation (AMC). The engine was engineered for fuel efficiency, smooth operation, and long life, not for performance. Total Duke engine production is estimated to be between 3.8 and 4.2 million units.
The Buick V6 is an OHV V6 engine developed by the Buick division of General Motors and first introduced in 1962. The engine was originally 198 cu in (3.2 L) and was marketed as the Fireball engine. GM continued to develop and refine the 3.8 L (230 cu in) V6, eventually and commonly referred to simply as the 3800, through numerous iterations.
Automobile accessory power can be transferred by several different means. However, it is always ultimately derived from the automobile's internal combustion engine, battery, or other "prime mover" source of energy. The advent of high-powered batteries in hybrid and all-electrical vehicles is shifting the balance of technologies even further in the direction of electrically powered accessories.
The Holden Caprice is a full-size car which was produced by Holden in Australia from 1990 to October 2017. The similar Holden Statesman, which was also introduced in 1990 as a model below the Caprice, was discontinued in September 2010. Between 1971 and 1984, Holden marketed their long-wheelbase sedans under the Statesman marque.
The Buick Park Avenue is a full-size car built by Buick. The nameplate was first used in 1975 for an appearance option package on the Electra 225 Limited. It became an Electra trim level in 1978 and its own model starting in the 1991 model year after the Electra was discontinued.
The Buick LeSabre is a full-size car made by the division Buick of General Motors from 1959 until 2005. Prior to 1959, this position had been retained by the full-size Buick Special model (1936–58). The "LeSabre", which is French for "the sabre", was Buick's mid-level full-size sedan above the Special but below the Electra during the 1960s then remained in its market position when the Electra was replaced with the Park Avenue. The LeSabre was available as a 2-door convertible, sedan or hardtop, a 4-door sedan or hardtop and station wagon throughout its production.
A belt is a loop of flexible material used to link two or more rotating shafts mechanically, most often parallel. Belts may be used as a source of motion, to transmit power efficiently or to track relative movement. Belts are looped over pulleys and may have a twist between the pulleys, and the shafts need not be parallel.
BAS is a category of automotive parallel hybrid technology that uses an electric motor to contribute power to the internal combustion engine's crankshaft via a serpentine belt. By mounting this motor generator unit in the conventional location traditionally used for the standard automotive alternator, it permits a low-cost method of adding mild hybrid capabilities such as start-stop, power assist, and mild levels of regenerative braking. BAS systems differ from other mild hybrid systems as they are not run off the vehicle's crankshaft.
The KV6 automotive petrol engine has a 24-valve quad-cam V6 configuration, and a pressurising variable-length intake manifold to add hot spots throughout the rev range. Variants exist in 2.0 to 2.5 litres capacities. These were built initially by Rover Group, then by Powertrain Ltd. KIA manufactured KV6 in Korea under licence. Production moved from the UK to China in 2005, re-designated NV6.
Underdrive is the slowing of the rate of rotation in a system, achieved by either making the crank or main (drive) pulley smaller or making the accessory (driven) pulley larger than the original diameter pulleys.
The following outline is provided as an overview of and topical guide to automobiles:
A free-piston engine is a linear, 'crankless' internal combustion engine, in which the piston motion is not controlled by a crankshaft but determined by the interaction of forces from the combustion chamber gases, a rebound device and a load device.
A harmonic damper is a device fitted to the free end of the crankshaft of an internal combustion engine to counter torsional and resonance vibrations from the crankshaft. This device must be an interference fit to the crankshaft in order to operate in an effective manner. An interference fit ensures the device moves in perfect step with the crankshaft. It is essential on engines with long crankshafts and V8 engines with cross plane cranks, or V6 and straight-three engines with uneven firing order. Harmonics and torsional vibrations can greatly reduce crankshaft life, or cause instantaneous failure if the crankshaft runs at or through an amplified resonance. Dampers are designed with a specific weight (mass) and diameter, which are dependent on the damping material/method used, to reduce mechanical Q factor, or damp, crankshaft resonances.
An alternator is a type of electric generator used in modern automobiles to charge the battery and to power the electrical system when its engine is running.