WEEK 5 PUSHPARAJ

A chassis is the load-bearing framework of an artificial object, which structurally supports the object in its construction and function. An example of a chassis is a vehicle frame, the underpart of a motor vehicle, on which the body is mounted; if the running gear such as wheels and transmission, and sometimes even the driver\'s seat, are included, then the assembly is described as a rolling chassis

vehicle:

In the case of vehicles, the term rolling chassis means the frame plus the \"running gear\" like engine, transmission, driveshaft, differential and suspension. An underbody (sometimes referred to as \"coachwork\"), which is usually not necessary for the integrity of the structure, is built on the chassis to complete the vehicle.

For commercial vehicles, a rolling chassis consists of an assembly of all the essential parts of a truck without the body to be ready for operation on the road. A car chassis will be different from one for commercial vehicles because of the heavier loads and constant work use. Commercial vehicle manufacturers sell \"chassis only\", \"cowl and chassis\", as well as \"chassis cab\" versions that can be outfitted with specialized bodies. These include motor homes, fire engines, ambulances, box trucks, etc.

In particular applications, such as school buses, a government agency like the National Highway Traffic Safety Administration (NHTSA) in the U.S. defines the design standards of chassis and body conversions.

An armoured fighting vehicle\'s hull serves as the chassis and comprises the bottom part of the AFV that includes the tracks, engine, driver\'s seat, and crew compartment. This describes the lower hull, although common usage might include the upper hull to mean the AFV without the turret. The hull serves as a basis for platforms on tanks, armoured personnel carriers, combat engineering vehicles, etc.

ENGINE:

A motorcycle engine is an engine that powers a motorcycle. Motorcycle engines are typically two-stroke or four-stroke internal combustion engines, but other engine types, such as Wankels and electric motors, have been used.

Although some mopeds, such as the VéloSoleX, had friction drive to the front tire, a motorcycle engine normally drives the rear wheel, power being sent to the driven wheel by belt, chain or shaft. Historically, some 2,000 units of the Megola were produced between 1921-1925 with front-wheel drive, and the modern Rokon, an all-terrain motorcycle with both wheels driven, has been produced since 1960.

Most engines have a gearbox with up to six ratios. Reverse gear is occasionally found on heavy tourers, for example, the Honda GL1600, and sidecar motorcycles, such as the Ural. The rider changes gears on most motorcycles using a foot-pedal and manual clutch, but early models had hand-levers. More recently, some have automatic or semi-automatic gearboxes.

Types

Almost all production motorcycles have gasoline internal combustion engines. Both four-stroke and two-stroke engines are used, but strict emission laws have led to far fewer two-strokes. A few have used Wankel rotary engines, but no Wankel bikes are currently in production. Motorcycle engines can be air-cooled or liquid-cooled and optionally include oil cooling as well. Some scooters use batteries and an electric motor. The 2009 TT races introduced a new category \'TTX\' (renamed as TT Zero) for electric bikes using fuel-cells or batteries.

Motorcycle engines can be mounted transversely; with the crankshaft aligned perpendicular to the frame or longitudinally, with the crankshaft parallel to the frame. Motorcycles with transversely mounted engines are more suited to have chain or belt final-drive. Motorcycles with longitudinally mounted engines are more suited for shaft final-drive.

Motor scooters often have the engine as part of the rear suspension, so the engine is not fixed rigidly to the mainframe. Instead, the combined engine-transmission-swingarm assembly is pivoted to follow the road surface and is part of the \"unsprung weight\". The chain final-drive of scooters runs in an oil-bath within the engine casings. \"Step-through\" motorcycles may have a rigidly fixed engine or may have a scooter-type arrangement.

V-twin

In a V-twin engine, the cylinders form a \"V\" around the crankshaft. A Vee-angle of 90°, as used by Ducati and Moto Guzzi, can give perfect primary and secondary balance, with a pleasingly irregular firing order. A lesser angle gives a more compact motor, but one which is prone to vibration, such as 42° (Indian), 45° (Harley-Davidson), 52° Honda, and 60° (Aprilia). Most V-twins have a single crankpin shared by side-by-side connecting rods so that the cylinders are slightly offset, but a variation is to have a single crankpin with \"fork & blade\" con-rods, to keep the cylinders in line. Non-90° V-twins may have offset crankpins to try to reduce vibration.

V-twins may be mounted either longitudinally with the cylinders protruding either side, like the Honda CX500 and Moto Guzzi, or transversely, such as Harley-Davidson, Ducati, or Aprilia. Transverse V-twins can raise difficulties in cooling the aft cylinder and in siting the airbox, battery, aft carburettor, and aft exhaust pipe