farm tractors and their management
TRANSCRIPT
Farm Tractors and their Management(2 Lectures)
Prepared by
Er.Uttam Raj Timilsina(MSc.Engineering IIT Roorkee)
Professor of Agricultural Engineering,AFU
Farm Tractors and their Management• Types of Farm Tractors
• Components of farm tractor
• Operation and Maintenance(O&M) of Tractor Systems
• Suitability and Tractor selection for Nepalese Agriculture
Farm Tractors
Tractors: It is a self propelled machine used for pulling or pushing
loads for tractive and stationary works.The name tractor is derived from Traction Motors in 1906 as Trac+tor or Tract+or.
It gets its driving force in combination with an engine and driving wheels.
Engine power is transmitted to the driving wheels through a series of inter linkages called power trains
Power trains consist clutch, transmission(gear box,) differential,final drives,(driving axles,wheels).
Tractor power is used through its power take off shaft called PTO shaft,pulley,hydraulic system and drawbar
Farm Tractor…..
Types of farm TractorsUtility Tractor or General purpose
Tractor:generally used for ploughing and driving any other equipments
Row crop TractorsOrchard type TractorsGarden type Tractor Industrial type TractorEarth moving TractorsTiller Tractors-Power Tillers/Two wheel tractors
Components of Farm Tractors
Tractor Chassis: where engine and all other systems units are mounted.
Engine
Control System:
Power Transmission system
Differential
Power take-off(P.T.O)system
Hydraulic System, Drawbar system
Farm implement hitching and pulling System
Components of Farm Tractors…
Tractor Chassis: where engine and all other systems units are mounted.It consists of Engine mounting pads,Clutch housingGear box housingFixing boltsFront cross memberChassis long membersFront cross member/front axleRear axleHitching frame/Trailer hitchinf, plow hitching,stationary machines hitching
Components of Farm Tractors…..
Engine
Power generation component
Fuel supply and circulation component
Engine cooling component
Lubrication component
Air cleaning component
Electrical component
Engine starting component
Tractor component…Steering
Tractor control system• Steering system: It consist of steering wheel,Steering shaft, steering
gear box, drip arms, side steering rod,steering livers(tie rod),stub axles,centre beam,beam extension,track rod etc
It perform the action to steer to move the tractor to right or left Two types of steering: Mechanical steering and hydraulic steering Mechanical steering is hard than hydraulic steering to operate Hydraulic steering or power steering is the advanced stage of
mechanical steering Hydraulic steering consist of hydraulic pump,and piston cylinder
system instead of stering gear box. It minimise the wear and tear of mechanical steering
Tractor control system contd…clutch
• Clutches: it is a device used to disconnect the tractor engine power
with power trains for changing gear It transmits power by means of friction between driving
element(engine) and driven elements(power trains) Located between engine and gear box and used to connect
or disconnect the engine drive to gear box The clutch assembly consists of driving member (flywheel)
fixed with crankshaft end and driven member called clutch plate
Clutch assembly consists of many parts as Fly wheel,driveplate,pressure plate,thrust spring,release liver,carbonblock, clutch pedal,cross shaft ,fork,pivot pin lever plate etc
Control system……clutch
Types of clutches-Single disc type or single plate clutch is dry type clutch.Driven plate is held against flywheel by means of spring loaded pressure plate-Multiple disc type or multiplate clutch is of hydraulic type with hydraulic pump.-consists of number of driving and driven plates alternately arranged.-Driving plates are fixed with flywheel -Driven plates are attached with clutch drum
Control system ..Brakes
Brake system:It is provided in the tractor wheel as known as front wheel brake,rear wheel brake in all wheel,hand brake, pedal brake to reduce the tractor speed as well as to stop the moving tractor when required
Types of brake-Mechanical brakes,Hydraulicbreaks(modern)
Break consists of assembly of many parts such as break pedal, push rod Master cylinder, wheel cylinder,disc wheel,break mechanism
Power Transmission System
Gear Box or Gear housing It is a unit connected after clutch and is provided to perform the functions/jobs of increasing or
decreasing the relative power as well as speed of tractor or any vehicle Types of gears are
-straight spur gear,-helical spur gear and- herring bone gears
Gear box consists three gangs of gear - main shaft gang or input shaft gang with main gear-Counter shaft or lay shaft gang with number of gears mounted on counter shaft(Lay shaft)- Output shaft or pinion shaft gang with number of gears mounted of pinion shaft
The gear actions are 3-5 forward gears (first gear,second gear,third,fourth gear ) with variable speed and one reverse gear with low and high speed gear
Main gear shift liver with shifting diagram of 1st,2nd,3rd,reverse ,neutral and high-low gear shift lever
For changing the gear from one situation to another, first should come to neutral position.
Gear box….
Reduction of speed through the gear box ranges between 1-1/5th at highest and lowest speed respectively
Generally tractor speed at top gear varies from 18-24 km/hr Method of gear shifting in gear box are of• crash mesh or sliding mesh gear shifting with shifter fork for sliding action at zero speed• ,constant mesh gear shifting with two shifter collars for sliding action at zero speed,• synchromesh gear shifting with synchronizer sleeves to avoid sound when shifting gear, bringing
two gear at same idle gear speed • Planetary type Mesh gear shifting (advanced) used in American and European tractor Gear ratio and speed ratio-when two meshing gear have same number of gear teeth and drive
each other, both runs at same speed and same torque with the gear ratioi of 1:1, and speed ratio of 1:1
When a smaller gear having 6 number of teeth is driving a bigger gear of 18 teeth, then smaller gear must have to revolve three time to complete one revolution of bigger gear with reduced speed of bigger gear and at such situation gear ratio is 6:18 or 1:3 and speed ratio is 3:1 with higher torque(force) delivered of 3 times more
When a bigger gear having 18 number of teeth is driving a smaller gear of 6 teeth, then smaller gear must have to revolve three time with the completion of one revolution of bigger gear with increased speed of smaller gear at such situation gear ratio is 18:6 or 3:1 and speed ratio is 1:3 with lower torque(force) delivered of one third.
It is a reverse output of speed , direction and torque relationship and vice versa
Power transmission….
Differential Differential assembly is fitted in the centre of rear axle
casing to perform or to do the two jobs as • To transmit the power from gear shaft at right angle to the
axle shaft to move the two rear wheel at same speed in a straight forward and backward motion
• To differentiate the speed of two rear wheel while tractor is taking left or right turn as outer wheel has to run faster than the inner wheel
Differential assembly consists of bevel pinion gear, ring or crown gear,differential side gears,differential pinions gear,spider,bearings and differential housing(pinion carrier)
Power Transmission…
Power take off(P.T.O) shaft PTO shaft is a standard fitting in all the tractors as special power transmission
system provided with a standard splined shaft at the rear of tractor after differential assembly system for special types of PTO operated machines for stationary as well as tractive works such as to run thresher,water lifting pump, centrifugal pumps,chaff cutter,electric moter,power generator,rice mills, flour mills,mowers,forage harvesters,combine etc
The PTO shaft is always kept covered at the exposed end to avoid accidents during operation
PTO drives consists of drive shaft, flexible couplings by the use of one or more universal joints,tractor pulley for belt drive rotary power transmission etc
PTO shaft is also provided with an additional gear unit and a tractor pulley to operate belt driven machines
The standard rpm developed at PTO shaft is 1000 rpm and directly proportionate to engine speed.
Hydraulic System
The hydraulic system of modern tractors consists of hydraulic pump,hydraulic cylinder and ram,safety and control valves, hand control lever,cross shaft,three pin hitch etc
The purpose of hydraulic system in a tractor is to control the position of the implements as to raise or to lower implements hydraulically while transporting it from one place to another and while operating in the field
In this system fluid as transmission oil is used and pressure is employed to do the work
Usually hydraulic pump, the most important part which develops a pressure of about 150 kg/sq.cm and other parts of the system are placed in the rear axle housing of the tractor
Hydraulic…
The hydraulic system is mainly used for operating a three point hitch which consists of two tension links(lower links) and the third compression link(upper link) connected to the implement from the tractor
Generally hydraulic operated three pin hitch are adjustable to vary the hitch and to level the implement in the horizontal plane
The implements like disc plough,disc harrow,cultivator can be lowered and raised from the tractor seat simply by operating the hand control lever to adjust the depth of plough of primary and secondary tillage implements as well as to raise the implements during turning of tractor in field.
Periodic Operation and Maintenance Service of Tractor Systems
• Servicing after each 10 working hours Check crankcase oil and fill it to the normal level mark indicated on the dip
stick Check the fuel level in the fuel tank and fill it if required Check water in the radiator and fill it if required Check the oil level in air cleaner,clean and refill it to the normal level
indicated on the bowl Check the battery terminals and water lavel in the battery,top up the
distilled water about 3mm above the plates Check the gear box oil level and refill it if necessary Grease the front axle spindles and the steering drag links Check front and rear tyre pressure,normally requires 2 kg/sq.cm in front
wheel tyre and 1 kg/sq.cm in rear wheel tyre Check all nuts and bolts to keep in normal tight Inspect the tractor carefully and ensure for no leakage of oil
• Servicing after each 60 hours of operation Check fan-belt tension and adjust it if required Check the water pump of cooling system Check the primary fuel filter,loosen the vent plug and drain
tap Check and adjust the brakes for proper operation Check transmission oil level Lubricate fan hub bearings,throttle control lever, engine
clutch release bearings and dynamo bearing Clean air cleaner Check the fuel line for any leakage Clean radiator fins
• Servicing after each 125 hours of operation
Drain engine sump oil and refill it with recommended grade of oil
Drain oil from fuel injection pump and refill it with fresh engine oil
Replace oil filter element
Drain and clean fuel filter
Check dynamo and starter terminals and wiring
Check oil level in gear box
• Servicing after each 250 hours of operation Replace lubricating oil filter element Repack the front wheel bearings with fresh grease Oil the startor and dynamo bearings Clean the sump strainer Clean the strainer of fuel sediment bowl and carryout
other servicing of fuel filter Check steering box oil level and grease the steering top
bearing Wash the fuel injection pump breather with kerosene Check the hydraulic oil level in hydraulic lift housing
• Servicing after each 500 hours of operation
Remove and clean the crank case breather assembly
Adjust the valve tappet clearance as specified in operator,s manuals
Drain,clean and flush radiator with soda water and refill
Renew the primary fuel filter element
Lubricate front axle centre pivot pin
Arrange to have fuel injectors serviced by dealer or workshop
• Servicing after every 1000 hours of operation Change the transmission oil Change the oil of steering gear box Drain the fuel tank and clean it Renew the secondary fuel filter element Remove the cylinder head cover and examine the valves springs and check
the tappet clearance Inspect the rocker arm assembly for proper lubrication Get the cylinder lines checked for wear and tear Get the crankshaft bearings checked for wear and tear Get the piston and rings checked for wear and tear Get rear axle bearing checked and repacked with recommended grade of
grease through dealer Clean front axle bearings and repack them with grease
Suitability and tractor selection for Nepalese Agriculture