The document provides an overview of tractor hydraulics, detailing the working principles, components, types of hydraulic systems, and the importance of maintenance. It explains how hydraulic systems operate based on Pascal's law and includes descriptions of key components such as pumps, valves, and motors. Additionally, it covers control methods for implements and emphasizes the need for regular maintenance to ensure system efficiency.

1. Tractor Hydraulics

2. Content
 Introduction
 Working principle
 Why Hydraulic system
 Parts of hydraulic system
 Types of hydraulic system
(a) Based on centre system
(b)Based on control
 Maintenance and repair

3. Introduction
 A unit responsible for lifting and lowering an agricultural
implement
 Function-draft control and weight transfer
 Fluid is confined inside pipelines, reservoir and cylinders
 Hydraulic pumps transfer the fluid from the reservoir to the
hydraulic system. This transfer raises the energy level of the
fluid by increasing its pressure. The motor provides the
power source for the pump

4. Working principle
The working principle of hydraulic system is based on pascal's law. This
law states that the pressure applied to an enclosed fluid is transmitted
equally in all directions. Small force acting on small area can produce
higher force on a surface of larger area.
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5. Why hydraulic system
 Simpler than mechanical linkage systems
 System is flexible enough
 Power can be engaged or disengaged using a simpler valve
 Input heavy forces can be controlled easily
 A good range of speed operation is possible
 Is safer than mechanical system

6. Parts of hydraulic system
 Reservoir
 Pump
 Valves
 Fluid
 Motor
 Hose
 Filter
 Cylinder
 Accumulator

7. Reservoir
It contains sufficient oil to move the piston for lifting the load
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8. Pump
 It forces the fluid from the reservoir to the cylinder
 There are several types of hydraulic pump, such as gear pump,
plunger pump, vane pump, and screw pump. Gear pump is
widely used in tractors. Gear pump can flow a bigger amount of
oil, compared to plunger pump. The oil pressure in the pump
varies from 150 to 200 kg/cm2.Schema
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9. Relief valve
Relief valves are used in hydraulic systems to limit the system
pressure to a specific set level. If this set level is reached, the
pressure relief valve responds and feeds the excess flow from
the system back to the tank
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10. Control valves
Control valve is a type of valve, which controls the movement
of hydraulic oil to have desired direction, magnitude and
speed of lifting. This helps to determine speed of movement
for the actuators.
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11. Hydraulic motor
A hydraulic motor converts hydraulic energy into
mechanical energy: a rotating shaft. It uses hydraulic
pressure and flow to generate torque and rotation.
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12. Hydraulic Hose
Hydraulic hose is specifically designed to convey hydraulic fluid to or
among hydraulic components, valves, actuators, and tools. It is typically
flexible, often reinforced and usually constructed with several layers of
reinforcement since hydraulic systems frequently operate at high or very
high pressures.
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13. Hydraulic filter
Hydraulic filters are used to protect your hydraulic system
components from damage due to contamination of oils
caused by particles
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14. Hydraulic accumulator
 A hydraulic accumulator stores fluid under pressure
 Accumulators can take a specific amount of fluid under
pressure and store it. The fluid is then released when it´s
required to perform a specific task in the hydraulic system
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15. Types of hydraulic systems
 Open centre system
 Close centre system
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16. Implement control
The tractor with a built in lift system is connected to the implement
through a specific type of mechanical linkage termed as three point
linkage and the system is known as mounted system. The implement
is connected to the tractor hydraulic system at two bottom links and
one top link. Both the bottom links are connected to two lift arms
through lift links. The lift arms are directly mounted on a rockshaft,
which is further connected to the piston rod. Any movement of the
piston is transferred to the bottom links. The top link is used for
connecting the third hitch point of the implement and is adjustable for
maintaining the implement level and suction angle. Load sensing for
the draft control can also be done through the top link, which is
spring, loaded. In some tractors the lower links are spring loaded for
draft sensing. Depending upon the soil condition and type of
operation, the mounted implement can be controlled either by
position control or draft control.

17. Position control
In this system, constant depth of ploughing is maintained by
automatic adjustment of draft of tractor. In this system the
control valve can be operated directly by the driver to raise
lower or hold an implement, mounted on the linkage at any
chosen height.

18. Draft Control
 Under this system of control, the implement is set for a
particular draft(drawbar pull) rather than depth. In varied
soil conditions the implement automatically takes more or
less depth to maintain the predetermined draft.
 Most of the indigenous tractors possess a draft control
system in addition to position control

19. Mixed position and draft control
It is also possible in some tractor (viz. HMT, Ford
etc. ) to suitable blend the response through
interlink mechanism so that a desired depth of
ploughing is maintained within closed limits and
draft control too is allowed to function for better
traction

20. Maintenance and repair of hydraulic system
For successful operation of any hydraulic system,
cleaning and periodic maintenance is very essential. If
the operator is alert and keeps the machine clean ,
refills clean oil , replaces or clean the filter regularly,
keeps the tubes and rubber hose tight and protect the
system from dust and other contaminants, the system
will undoubtedly work efficiently with less trouble