04-08-2014, 12:34 PM
VEHICLE:
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INTRODUCTION
Vehicles, derived from the Latin word, vehiculum, are non-living means of transport. Most often they are manufactured (e.g. bicycle, cars, motorcycles, trains, ships, boats, and aircraft), although some other means of transport which are not made by humans also may be called vehicles; examples include icebergs and floating tree trunks.
Vehicles may be propelled or pulled by animals, for instance, a chariot, a stagecoach, a mule-drawn barge, or an ox-cart. However, animals on their own, though used as a means of transport, are not called vehicles, but rather beasts of burden or draft animals. This distinction includes humans carrying another human, for example a child or a disabled person.
A rickshaw is a vehicle that may carry a human and be powered by a human, but it is the mechanical form or cart that is powered by the human that is labeled as the vehicle. For some human-powered vehicles the human providing the power is labeled as a driver.
Vehicles that do not travel on land often are called craft, such as watercraft, sail craft, aircraft, hovercraft, and spacecraft.
PNEUMATICS
The word ‘pneuma’ comes from greek and means breather wind. The word pneumatics is the study of air movement and its phenomena is derived from the word pneuma. Today pneumatics is mainly understood to means the application of air as a working medium in industry especially the driving and controlling of machines and equipment.
Pneumatics has for some considerable time between used for carrying out the simplest mechanical tasks in more recent times has played a more important role in the development of pneumatic technology for automation.
Pneumatic systems operate on a supply of compressed air which must be made available in sufficient quantity and at a pressure to suit the capacity of the system. When the pneumatic system is being adopted for the first time, however it wills indeed the necessary to deal with the question of compressed air supply.
PRODUCTION OF COMPRESSED AIR
Pneumatic systems operate on a supply of compressed air, which must be made available in sufficient quantity and at a pressure to suit the capacity of the system. When pneumatic system is being adopted for the first time, however it wills indeed the necessary to deal with the question of compressed air supply.
The key part of any facility for supply of compressed air is by means using reciprocating compressor. A compressor is a machine that takes in air, gas at a certain pressure and delivered the air at a high pressure. Compressor capacity is the actual quantity of air compressed and delivered and the volume expressed is that of the air at intake conditions namely at atmosphere pressure and normal ambient temperature.
RECIPROCATING COMPRESSORS
Built for either stationary (or) portable service the reciprocating compressor is by far the most common type. Reciprocating compressors lap be had is sizes from the smallest capacities to deliver more than 500m3/min.In single stage compressor, the air pressure may be of 6 bar machines discharge of pressure is up to 15bars.Discharge pressure in the range of 250bars can be obtained with high pressure reciprocating compressors that of three & four stages. Single stage and 1200 stage models are particularly suitable
For applications, with preference going to the two stage design as soon as the discharge pressure exceeds 6 bars, because it in capable of matching the performance of single stage machine at lower costs per driving powers in the range.
SYNCHRONIZED TRANSMISSION:
Modern gearboxes are constant mesh, i.e., all input and drive gears are always in mesh. Only one of these meshed pairs of gears is locked to the shaft on which it is mounted at any one time, while the others are allowed to rotate freely. This greatly reduces the skill required to shift gears.
Most modern cars are fitted with a synchronized gear box, although it is entirely possible to construct a constant mesh gearbox without synchromesh, as found in a motorcycle, for example. In a constant mesh gearbox, the transmission gears are always in mesh and rotating, but the gears are not rigidly connected to the shafts on which they rotate. Instead, the gears can freely rotate or be locked to the shaft on which they are carried. The locking mechanism for any individual gear consists of a collar (or "dog collar") on the shaft which is able to slide sideways so that teeth (or "dogs") on its inner surface bridge two circular rings with teeth on their outer circumference: one attached to the gear, one to the shaft (one collar typically serves for two gears; sliding in one direction selects one transmission speed, in the other direction selects the other) when the rings are bridged by the collar, that particular gear is rotationally locked to the shaft and determines the output speed of the transmission.
CONTROL UNIT:
In pneumatic device is an air-operated device used for many small operations. It is a portable one. Compressed air is the source of energy for this device. The compressed air is allowed through the nozzle. Thick tubes interconnect the parts by T cap. The clamps are used at the connecting parts to prevent leakage. In thread parts seals are used to prevent leakage.
Here the compressed air form the compressor firstly enters the Control unit. In the control unit the pressure of the air is controlled unit the pressure of the air is controlled and sent to the valve and the cylinder to operated the gear which press the key for the changing the gear in the vehicle. The above process is carry out by the simple chip name microcontroller.
WORKING PRINCIPLE
Here we are using the pneumatic cylinder for gear changing process the compressed air from the compressor reaches the solenoid valve. The solenoid valve changes the direction of flow according to the signals from the timing device. The compressed air passes through the solenoid valve and it is admitted into the front end of the cylinder block. The air pushes the piston for the pneumatic cylinder block to increase and decrease the gear. The gear changing mechanism is working with the help of control unit which receives the signal from the button. Whenever the button is operated the pneumatic cylinder is actuated and gear is applied in that same way by pressing another button gear is reduced. Hence we can control the gears in an efficient manner. Here the control unit is nothing but the small chip called micro controller it’s already programmed and feed in the chip for working of our process of gear changing mechanism.
CHAPTER – 5
MERITS AND DEMERITS
MERITS
Automatic method
Avoids confusion of changing gears.
Speed level matches with the gear changing mechanism.
System is helpful for the drivers.
Avoids fear while driving the vehicle.
DEMIRTS
Cylinder stroke length is constant
Need a separate compressor
APPLICATION
In this we are applicable in all types of four wheelers, trucks etc..,