离合器汽车制动系统外文文献翻译中英文翻译外文翻译.docx

1、离合器汽车制动系统外文文献翻译中英文翻译外文翻译3.1 Clutch The engine produces the power to drive the vehicle. The drive line or drive train transfers the power of the engine to the wheels. The drive train consists of the parts from the back of the flywheel to the wheels. These parts include the clutch, the transmission, t

2、he drive shaft, and the final drive assembly. The clutch which includes the flywheel, clutch disc, pressure plate, springs, pressure plate cover and the linkage necessary to operate the clutch is a rotating mechanism between the engine and the transmission. It operates through friction which comes f

3、rom contact between the parts. That is the reason why the clutch is called a friction mechanism. After engagement, the clutch must continue to transmit all engine torque to transmission depending on the friction without slippage. The clutch is also used to disengage the engine from the drive train w

4、henever the gears in the transmission are being shifted from gear ratio to another.To start the engine or shift the gears, the driver has to depress the clutch pedal with the purpose of disengagement the transmission from the engine. At that time, the driven members connected to the transmission inp

5、ut shaft are either stationary or rotating at a speed that is slower of faster than the driving members connected to engine crankshaft. There is no spring pressure on the clutch assembly parts. So there is no friction between the driving members and driven members. As the driver lets loose the clutc

6、h pedal, spring pressure increase on the clutch parts. Friction between the parts also increases. The pressure exerted by the springs on the driven members is controlled by the driver through the clutch pedal and linkage. The positive engagement of the driving and driven members is made possible the

7、 friction between the surfaces of the members. When full spring pressure is applied, the speed of the driving and driven members should be the same. At the moment, the clutch must act as a coupling device and transmit all engine power to the transmission, without slipping. However, the transmission

8、should be engaged to the engine gradually in order to operate the car smoothly and minimize tensional shock on the drive train because an engine at idle just develop little power. Otherwise, the driving members are connected with the driven members too quickly and the engine would be stalled. The fl

9、ywheel is a major part of the clutch. The flywheel mounts to the engines crankshaft and transmits engine torque to the clutch assembly. The flywheel, when coupled with the clutch disc and pressure plate makes and breaks the flow of power the engine to the transmission. The flywheel provides a mounti

10、ng location for the clutch assembly as well. When the clutch is applied, the flywheel transfers engine torque to the clutch disc. Because of its weight, the flywheel helps to smooth engine operation. The flywheel also has a large ring gear at its outer edge, which engages with a pinion gear on the s

11、tarter motor during engine cranking. The clutch disc fits between the flywheel and the pressure plate. The clutch disc has a splinted hub that fits over splints on the transmission input shaft. A splinted hub has grooves that match splints on the shaft. These splints fit in the grooves. Thus, the tw

12、o parts held together. However, back and forth movement of the disc on the shaft is possible. Attached to the input shaft, the disc turns at the speed of the shaft. The clutch pressure plate is generally made of cast iron. It is round and about the same diameter as the clutch disc. One side of the p

13、ressure plate is machined smooth. This side will press the clutch disc facing are against the flywheel. The outer side has shapes to facilitate attachment of spring and release mechanism. The two primary types of pressure plate assemblies are coil spring assembly and diaphragm spring. In a coil spri

14、ng clutch the pressure plate is backed by a number of coil springs and housed with them in a pressed steed cover bolted to the flywheel. The spring pushes against the cover. Neither the driven plate nor the pressure plate is connected rigidly to the flywheel and both can move either towards it o awa

15、y. When the clutch pedal is depressed a thrust pad riding on a carbon or ball thrust bearing is forced towards the flywheel. Levers pivoted so that they engage with the thrust pad at one end and the pressure plate tat the other end pull the pressure plate back against its springs. This releases pres

16、sure on the driven plate disconnecting the gearbox from the engine. Diaphragm spring pressure plate assemblies are widely used in most modern cars. The diaphragm spring is a single thin sheet of metal which yields when pressure is applied to it. When pressure is removed the metal spring back to its

17、original shape. The center portion of the diaphragm spring is slit into numerous fingers that act as release levers. When the clutch assembly rotates with the engine these weights are flung outwards by centrifugal plate and cause the levers to press against the pressure plate. During disengagement o

18、f the clutch the fingers are moved forward by the release bearing. The spring pivots over the fulcrum ring and its outer rim moves away from the flywheel. The retracting spring pulls the pressure plate away from the clutch plate thus disengaging the clutch.When engaged the release bearing and the fi

19、ngers of the diaphragm spring move towards the transmission. As the diaphragm pivots over the pivot ring its outer rim forces the pressure plate against the clutch disc so that the clutch plate is engaged to flywheel.The advantages of a diaphragm type pressure plate assembly are its compactness, low

20、er weight, fewer moving parts, less effort to engage, reduces rotational imbalance by providing a balanced force around the pressure plate and less chances of clutch slippage. The clutch pedal is connected to the disengagement mechanism either by a cable or, more commonly, by a hydraulic system. Eit

21、her way, pushing the pedal down operates the disengagement mechanism which puts pressure on the fingers of the clutch diaphragm via a release bearing and causes the diaphragm to release the clutch plate. With a hydraulic mechanism, the clutch pedal arm operates a piston in the clutch master cylinder

22、. This forces hydraulic fluid through a pipe to the cutch release cylinder where another operates the clutch disengagement mechanism by a cable. The other parts including the clutch fork, release bearing, bell housing, bell housing cover, and pilot bushing are needed to couple and uncouple the trans

23、mission. The clutch fork, which connects to the linkage, actually operates the clutch. The release bearing fits between the clutch fork and the pressure plate assembly. The bell housing covers the clutch assembly. The bell housing cover fastens to the bottom of the bell housing. This removable cover

24、 allows a mechanic to inspect the clutch without removing the transmission and bell housing. A pilot bushing fits into the back of the crankshaft and holds the transmission input shaft.3.2 Brake SystemThe breaking system is the most important system in cars. If the brakes fail, the result can be dis

25、astrous. Brakes are actually energy conversion devices, which convert the kinetic energy (momentum) of the vehicle into thermal (heat). When stepping on the brakes, the driver commands a stopping force ten times as powerful as the force that puts the car in motion. The braking system can exert thous

26、ands of pounds of pressure on each of the four brakes. The brake system is composed of the following basic components: the “master cylinder” which is located under the hood, and is directly connected to the brake pedal, converts driver foots mechanical pressure into hydraulic pressure. Steel “brake

27、lines” and flexible “brake hoses” connect the master cylinder to the “slave cylinders” located at each wheel. Brake fluid, specially designed to work in extreme condition, fills the system. “Shoes” and “Pads” are pushed by the salve cylinders to contact the “drum” and “rotors” thus causing drag, whi

28、ch (hopefully) slows the car. The typical brake system consists of disk brakes in front and either disk or drum brakes in the rear connected by a system of tubes and hoses that link the brake at each wheel to the master cylinder. Stepping on the brake pedal, a plunger is actually been pushing agains

29、t in the master cylinder which forces hydraulic oil (brake fluid) through a series of tubes and hoses to the braking unit at each wheel. Since hydraulic fluid (or any fluid for that matter) cannot be compressed, pushing fluid through a pipe is just like pushing a steel bar through pipe. Unlike a ste

30、el bar, however, fluid can be directed through many twists and turns on its way to its destination, arriving with the exact same motion and pressure that it started with. It is very important that the fluid is pure liquid and that there is no air bubbles in it. Air can compress which causes spongine

31、ss to the pedal and severely reduced braking efficiency. If air is suspected, then the system must be bled to remove the air. There are “bleeder screws” at each wheel and caliper for this purpose. On disk brakes, the fluid from the master cylinder is forced into a caliper where it pressure against a

32、 piston. The piton, in-turn, squeezes two brake pads against the disk (rotor) which is attached to the wheel, forcing it to slow down or stop. This process is similar to the wheel, causing the wheel to stop. In either case, the friction surface of the pads on a disk brake system, on the shoes on a d

33、rum brake convert the forward motion of the vehicle into heat. Heat is what causes the friction surfaces (lining) of the pads and shoes to eventually wear out and require replacement. Brake fluid is special oil that has specifics properties. It is designed to withstand cold temperatures without thickening as well as very high temperatures with