The English InstructionDump TruckA dump truck or production truck is a truck used for transporting loose material(such as sand,gravel or dirt)for construction.A typical dump truck is equipped with a hydraulically operated open-box bed hinged at the rear,the front of which can be lifted up to allow the contents to be deposited on the ground behind the truck at the site of delivery.In the UK the term applies to off-road construction plant only and the road vehicle is known as a tipper.Standard Dump TruckA standard dump truck is a full truck chassis with a dump body mounted to the frame.The dump body is raised by a hydraulic ram mounted forward of the front bulkhead,between the truck cab(traction unit)and the dump body (semi-trailer).The tailgate can be configured to swing on hinges or it can be configured in the “High Lift Tailgate” format where in pneumatic rams lift the gate open and up above the dump body.A standard dump truck has one front axle and one or more rear axles which typically have dual wheels on each side.Common configuration for a standard dump truck include the six wheeler which has one rear axle,the ten wheeler with two rear axles and the tri-axle with three rear axles.These are mainly found in inner cities and in the Deep South. The short wheelbase of a standard dump truck makes it more maneuverable than the higher capacity semi-trailer dump trucks.Off-road Dump Trucks Off-road dump trucks more closely resemble heavy construction equipment or engineering vehicles than they do highway dump trucks.They are used strictly off-road for mining and heavy dirt hauling jobs. The term DumpTruck is not generally used by the mining industry or by the manufactures that build these machines.The more appropriate US term for this strictly off road vehicle is Haultruck.The classification bottom and side for example,describing how the loaded material is discharged once loaded.In the case of the Haul truck illustrated,a Liebherr T 282B the load is discharged to the rear,designing this particular vehicle as an end dump.Bottom dump normally describes a trailer that discharges its load by opening two clam shell doors under the load space,in some examples several trailers(road train)are pulled by one truck mainly these are on road machines.The only remaining example of what is described as a unitized bottom dump coal hauler is manufactured by Kress Corporation.This large capacity truck is used for the transportation of coal from a loading device directly to a power station or bulk storage area.Winter Service Vehicle Many winter service vehicle units are based on dump trucks to allow the placement of ballast to weigh the truck down or to hold salt for spreading on the road.Semi Trailer and Dump Truck A semi end dump is a tractor-trailer combination where in the trailer itself contains the hydraulic hoist.A typical semi end dump has a 3-axle tractor pulling a 2-axle semi-trailer.The key advantage of a semi end dump is rapid unloading.A key disadvantage is that they are very unstable when raised in the dumping position limiting their use in many applications where the dumping location is uneven or off level.Main Component Parts of Tractor Automobile Both the tractor and the automobile are complex self-propelled machines consisting of separate interacting machanisms and units that can be combined into certain groups. The arrangement of the main component parts of the tractor is shown in Fig.2.Irrespective of particular design features,all tractors consist of engine,drive line,running gear,steering mechanism,working attachments and auxiliary equipment. The engine converts thermal energy into mechanical energy. The drive line comprise a set of mechanisms which transmit the torque developed by the engine to the driving wheels or tracks and change the driving torque both in magnitude and direction,The drive line includes the cluth,flexible coupling,transmission and rear axle. The cluth serves to disconnect the engine shaft from the transmission for a short period of time while the drivers is shifting gears and also to connect smoothly the flow of power from the engine to the driving wheels or tracks when starting the tractor from rest.The flexible coupling incorporates elastic elements allowing connecting the cluth shaft and the transmission drive shaft with a slight misalignment The transmission makes it possible to change the tractor by engaging different pairs of gears.With the direction of rotation of the engine shaft remaining the same,the transmission enables the tractor to be put in reverse. The rear-axle mechanisms increase the driving torque and transmit it to the driving wheel or tracks at right angles to the drive shaft.In most tractors,the rear also comprises brakes. In the wheeled tractor,as distinct from its crawler counterpart,the drive line includes the differential which enzbles the wheels to revolve with different speeds when making turns or