Er. Uttam Raj Timilsina(MSc.Engineering,IIT Roorkee) Professor of Agricultural Engineering,Agriculture and Forestry University (AFU), Rampur, Chitwan, Nepal uttamrajtimilsina@gmail.com *All Right Reserved** Uploaded and Shared by AgriYouthNepal

1. Farm Tractors and their
Management(2 Lectures)
Prepared by
Er.Uttam Raj Timilsina(MSc.Engineering IIT Roorkee)
Professor of Agricultural Engineering,AFU

2. 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

3. 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

4. Farm Tractor…..
 Types of farm Tractors
Utility Tractor or General purpose
Tractor:generally used for ploughing and driving
any other equipments
Row crop Tractors
Orchard type Tractors
Garden type Tractor
Industrial type Tractor
Earth moving Tractors
Tiller Tractors-Power Tillers/Two wheel tractors

5. 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

6. Components of Farm Tractors…
Tractor Chassis: where engine and all other systems
units are mounted.It consists of
 Engine mounting pads,
Clutch housing
Gear box housing
Fixing bolts
Front cross member
Chassis long members
Front cross member/front axle
Rear axle
Hitching frame/Trailer hitchinf, plow
hitching,stationary machines hitching

7. 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

8. 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

9. 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,drive
plate,pressure plate,thrust spring,release liver,carbon
block, clutch pedal,cross shaft ,fork,pivot pin lever plate etc

10. 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

11. 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,Hydraulic
breaks(modern)
Break consists of assembly of many parts such as
break pedal, push rod Master cylinder, wheel
cylinder,disc wheel,break mechanism

12. 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.

19. 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

28. 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)

35. 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.

38. 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

42. 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.

44. 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

45. • 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

46. • 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

47. • 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

48. • 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

49. • 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

50. Suitability and tractor selection for
Nepalese Agriculture