Dumper

Classification

• On the basis of dumping1. Rear discharge dumper • Rear end tractor trailer• Rear end truck type dumper1. Side discharge dumper2. Bottom discharge dumper• On the basis of frame 1. Rigid frame dumper2. Articulated dumper• On the basis of capacity1. Small capacity dumper;- up to 50 tonnes2. Medium capacity dumper;- 50- 100 tonnes3. Large capacity dumper;- 100-250 tonnes4. Giant dumper; more than 250 tonnes

Rear discharge dumper

• In this type the main body, which accept the material from excavator is placed on the rear part of operators cabin and discharges material through the rear portion of the equipment

• Rear end body is tilted on the rear side by means of telescopic types hydraulic jacks,

• upper end of which are fitted to the bottom of the body while lower ends are attached to the chasis of the equipment

• The rear end after discharging material returns to its original position on retracting telescopic jacks

Rear discharge dumper

• Rear end tractor trailer;- a trailer body mounted on two wheels is usually attached at the rear side of the tractor

• Rear end truck type dumper

Rear discharge dumper

Side discharge dumper

Side discharge dumper

• They deliver material over the drive tires• Discharging of material is achieved by hoisting

system by1. Integral hydraulic system2. By external sky hook arrangement

Bottom discharge dumper

Bottom discharge dumper

• the bottom dump dumper consist of a diesel powered prime mover fitted with a large trailer at the rear end mounted on two large wheels , the trailer unit has drop bottom or clame shell type doors, the are actuated by double acting single hydraulic cylinder

construction

(1) DUMP BODY TAILGATE. A panel, at the rear of the dump body, which can be opened from the top or bottom.(2) DUMP BODY DEBRIS COVER. A cover used to prevent loose cargo (sand, gravel,etc.) from being blown out of the dump body.(3) DUMP BODY CAB PROTECTOR. Protects the cab from damage caused by shifting loads.(4) DUMP BODY LIFT CYLINDER. A hydraulic cylinder which is used to raise and lower the dump body

CONSTRUCTION• The main assemblies are 1. The chassis;- includes frame, suspension system, wheels and tyres2. Body assembly3. The power train ;- engine, clutch, transmission drive shaft and

differential4. hydraulic system for steering and body hoisting, braking and air

system

Wheel

• The wheel mainly consist of brake shoe assembly.• Tyres are fitted to these assembly• Brake shoes assembly are two types1. Expanded shoe type2. Disk brake type

Expanded shoe type brake• This consist of two semicircular shoes held in position by a

piston cylinder arrangements• The piston cylinder are actuated by pressurised hydraulic

fluid• Liners are secured on the outer periphery of the brake

shoes• Brake shoes are held in retracted position by return spring• as the brake pedal is pressed , the pistons along with the

shoes expands outwards and stop rotating drum of the wheels. When the effort is withdrawal , the shoes are retracted to their previous original position their by releasing the brake

The chassis;- includes frame, suspension system, wheels and tyres• Frame ;- are made from channels and braced. the are made of special alloy steel

with integral front dumper. the length of the channel section and other dimensions , the no of braced members and their profile depends on individual design

suspension system

• To save the frame body suspension system are used• Types of suspension system1. Semi elliptical leaf spring2. Suspension cylinder systemSemi elliptical leaf spring• Springs in the form of thin leaves are placed one on the top of

another and are bolted by means of U- bolt. One end of the spring is rigidly connected to the chassis by means of a shaknle pin.

• During deflection the spring extends towards the shankle pin side, where by adjustment of the load and deflection are made• These are mostly used in small dumper up to 25 tonnes capacity

Suspension cylinder system

• These consist two pars 1. A stationary cylinder;- is secured to the dumper frame or chassis at the top or at

the side and a piston is attached to the spindle which is connected to wheel mounting s

• The piston plays inside the cylinder , which divides the cylinder into two parts 1. The chamber above the piston head ;- is the upper chamber , which consist a

layer of oil for lubricating as well as to maintain a gas tight sealing of piston head. The rest of the chamber is fitted with nitrogen gas

Lower chamber;- contains air only at atmospheric conditions. The piston used is is hollow one and contains specified amount of oilAs the loads comes on the dumper the piston tends to move upward. The

compressed nitrogen gas forces oil from the piston top through drilled holes in the piston wall and out of the outer lower chamber surrounding the piton

When piston moves downwards due to withdrawal or discharging of material , oil in the oputer chamber is drawn back to the top of the piston. Compressed nitrogen prevents extreme prevents extreme downward movement

tyres• There are two types of tyre1. Tubeless tyre2. tubes tyre

tyres

• Tubeless tyres This consist of a tyre body and a special inner liner. This is designed to hold air instead of an inflated rubber tube. The body is made of an air-tight cord fabric to retain air. Tubeless tyres are light in weight and do not get heated as fast or as much as tubed tyres. Periodic inspection is necessary, specially to check for nails, etc. that could damage or puncture the tyre.

• Tubed tyre this design provides for an inner tube that retain air inflates the tyre. The tube is an endless ruber tube with a valve. Compressed air is introduced through the valve and is retained inside tube under pressure. In some cases a flap is used between the tube and the rim

• All tyres in heavy earth moving machinery consist of the following

• Beads:- they are bundles of strong steel wire placed at the inner circle of the tyre. They prevent any changes in tyre shape that would interfere during fitting on the rim

• Core body:- this is the fabric body of the tyre that provides the strength to hold the internal pressure which supports the load.

• Piles:-Piles are the individual fabric layer in the cord body. They are usually looped around the beads.

• Tread:- this is thick rubber layer surrounding the core body. It is designed to provide tracton. Cushioning qualities and cut resistance.

• Side walls:- the side of the tyre, that is between tread and beads. This is mainly used as protection coating on the sides.

CAB

• Operator’s cabin are usually rubber mounted, fully enclosed chamber. Wind shield of tough glass is fitted at the front and a window vent and door is placed at the side. It is usually placed at the front left hand side of the vehicle

Body assembly.

• The dump bodies used in dumpers are of two types, 1. the rectangular section body, and2. the deep V-shaped body.• RECTANGULAR SECTION BODY• The shape of this type of body is rectangular box pattern, the cab shield is welded at the

front, which protects the operator’s cab during the loading of the dumper. This is provided with a tailgate at its rear end. Which is mounted on the rear top portion of the body by hinge joints. There is a locking arrangement of the gate at the rear bottom end of the body. The tailgate carries two locking pins at the two sides of the bottom portion of the gate.

• Locking of the door is achieved by inserting the pins in between the locking arms with the help of locking lever. When the body is tilted on its back the gate is opened by operating the lever and the material is discharged

• The shape of body resembles to letter V . The cab shield is welded at the front . There is no tail gate and desined for heavy duty

• Made of high tensile steel • The bottom plate thickness is approximately

16 mm and side and front wall 10mm thickness

POWER TRAIN• All the dumpers are rear wheel drive• Power transmission are three types1. Transmission with gear system2. Transmission with hydraulic system3. Transmission with electrical drive

Transmission with gear system

• The engine delivers the power to the gear box through mechanical clutch or torque convertor

• The output shaft of the gear box connected to the universal joint propeller shaft and again with another universal joint which is connected to the differential

• The differential finally drive delivers power to the wheel through final drive• It has 6 forward gear and one reverse gear

Transmission with hydraulic system

• Used for all types of dumper up to 100 tonnes capacity• The engine delivers the power to the torque convertor and hydraulic

transmission system• The output shaft of the torque convertor connected to the universal joint

propeller shaft and again with another universal joint which is connected to the differential

• The differential finally drive delivers power to the wheel through final drive• It has 6 forward gear and one reverse gear• Due to presence of Torque convertor The vehicle can accelerate and decelerated• automatic shifting gear• Trans mission subjected to less shift Shock there by increase life of engine

Transmission with electrical drive• This type of transmission is used in high capacity Dumpers• Engine drive a generator , which supplies power to two or four wheel motors

eliminating use of clutches, gear box, convertor, differential• The motor are driven by DC power and sped is controlled by means of stepping

resister in the rotor circuits• The Dc motor is cooled by a mechanically driven fan• The drive gear and reduction gear are assembled and installed as a single unit• High transmission efficiency and less noise in the system• This machine is less expensive and less maintenance• The breaking system is disc type which is provided with electro dynamic

retarding system

Differential

• The main function of differential is to adjust the speed and torque of wheel depending on situation

• When a vehicle travel around a corner , the distance travel by outer wheel is greater than inner wheels.

• If the wheel are mounted on dead axel , so that they turn independely of each other like front wheel , they will turn in different speed to compensate for the difference in travel

• If however the wheels are driven positively by the engine , a device is necessary which will permit them to revolve at different speeds without interfering with propulsion of the vehicle

• to accomplish this purpose a system of gears called the differential is provided

Differential

Dumper air system• The air system consist of the following air circuits1. Main air circuit2. Hydraulic tank air circuits3. Parking brake air circuits4. Dynamic brake air circuits5. Air over hydraulic brake circuits

Main air circuit

• The air circuit provides air pressure for the operation and control of the air system as a whole

• The component used in the circuit are1. Engine air cleaner and service indicator2. Air compressor3. Auto drain valve4. Un loader valve5. Mai air tank6. Shut off cock7. Safety valve

Main air circuit

• Air sucked through the air cleaner is allow to pass through the auto drain valve. this valve separates the moisture from the air and fairly dry air passes in the forward direction.

• Air is now allowed to pass through an uploader valve to relive the compressor pumping load when normal operating air pressure has been attainted in the system and to reestablish compression when the reservoir air pressure falls below the minimum pressure

• The main tank is provided with a safety valve and a shutt off valve. The pressure setting of the safety valve is 9.2 Kg/ cm2

Hydraulic tank air circuits

• The purpose of this circuit is to provide air pressure over the hydraulic tank thereby helping in the flow of the hydraulic fluid from the tank.

• The circuit consist of pressure reducer valve a hand control valve , a hydraulic tank , pressure relief valve

• air from the main tank is allowed to pass through the pressure reduce valve ,when air pressure is reduced to between 0.56-0.7 Kg/cm2. this air passes through the hand control valve in the hydraulic tank

• During the hoisting of the main body air pressure help in discharging the fluid from the tank to the hoist cylinder . When the body is lowered the fluid reenters the tank, causing air to compressed and then escape through relief valve within tanks thus preventing the buildup of pressure

Parking brake air circuits• This circuit consist of 1. Parking brake valve2. Quick relief valve3. Parking brake chamber4. Low pressure warning switchThis operates parking brake chamber ,which in turn operate the brake shoe.•The chamber is a spring loaded air cylinder . With no air pressure applied to the cylinder , the spring retract the piston assembly and applies the brake.•With the application of air pressure to the cylinder the spring pressure overcome and the piston assembly extends and release the parking brake•When the control valve is operated to apply the brake the value allows all the air to be expelled into the atmosphere from the brake chamber , there by allowing the pinion to move forward by spring force , which in turn moves the push rod and the brake is applied

Dynamic brake air circuits

• When the brake pedal is depressed air pressure is directed to the top of the piston held against a spring force in the brake valve.

• As the piston travels downwards the combined inletexaust valve is shifted off its seat and air enters directly to actuate the roto chamber

• This air pressure entering the roto chamber act against a piston forcing its to move against a return spring pressure to actuate the hydro retardar valve on the transmission.

• As the air pressure reduces the piston is forced back and the retarder returns to the designated state

Air over hydraulic brake circuits

• This circuits consist of the following components1. Two reservoir2. Dual tradel valve3. Two emergency relay valves4. six slave servo and master cylinder brake assemblies for

the wheel5. Two limiting and quick release valves6. Dry and slippery road control valve( hand operated)7. brake lock control valve

Air over hydraulic brake circuits operation• The two emergency relay valves maintain proper air pressure of

each reservoir during the use of brake. When the brake pedal is depressed, air from one of the reservoirs passes through the emergency relay valve to the primary section of the brake valve. Air from the other reservoir also flows through another emergency valve to the secondary section of the brake valve. Air pressure entering the emergency relay valve causes air to flow out from the reservoir to the slave servo of the brake circuit. Air pressure in the servo operates the master cylinder. Hydraulic pressure from the master cylinder actuates the wheel cylinder of the brake assemblies. One air circuit controls the operation of the hydraulic circuit for activation the brake shoes at the rear of each brake assembly, while the other circuit operates the hydraulic circuit made for the front of each brake assembly.

Causes of tire damage • Under or Over Inflation Tyres that are under inflated or over inflated can affect your tyre life, driving

comfort, traction and braking. Under inflation generates excessive flexing of the tyre casing, which results in overheating, increase of rolling resistance and premature wear. In extreme cases, under inflation can cause tyre damage. Likewise, over inflation can reduce tyre life, reduce grip and create irregular wear.

Driving at Speed• Driving at high speeds has a greater chance of causing tyre damage than at low

speeds. If contact is made with a road hazard, it has a greater chance of causing tyre damage.

• Driving at speed will cause the tyre a greater build up of heat, which can cause tyre damage.

• Overloading• To ensure that your tyres are not overloaded, read the load index of your tyres,

which is found on the tyre sidewall. Do not exceed the load capacity relative to this load index. Tyres that are loaded beyond their maximum loads can build up excessive heat that may result in sudden tyre destruction.