Hydraulic Drive Flashcards
Usually is characterized in operating
on heavy load but of slower response speed as compared with
pneumatic power transmission.
Hydraulic Power Transmission
This power transmission system can be found in lifting and moving
components of tractors and heavy equipment and machinery. An
example of this is when adjusting the depth of plowing and harrowing
in tillage equipment, when raising the header of combines, and many
others.
Hydraulic power transmission
A transmission drive system that uses pressurized hydraulic fluid to
drive machinery. It transfers hydrostatic flow and pressure of
energy, not of the kinetic energy.
HYDRAULIC-DRIVE SYSTEM
Advantages of hydraulic drive system
- Small in size and light in weight;
- High stiffness, high precision, and fast response;
- Large driving force, suitable for heavy load and direct driving;
- Greater flexibility of control and capability of obtaining an infinite
number of speeds between zero and maximum; - Possible to make provision for automatic reduction of the
delivery of a feed pump as the resistance of movement of a tool
increases; - Quick reversal without shock;
- Simple and efficient control, both manually and automatically;
- Silent operation with automatic lubrication by the transmission
oil, self-cooling and long life; - Lower power consumption which adjusts automatically to meet
resistance; - Safety ensured with the use of relief valves; and
- Life tool on hydraulically-operated machine is increased by as
much as 50%.
Limitations of hydraulic drive system
- Hydraulic systems require intensive and periodic maintenance;
- Systems frequently require parts with a very high degree of
precision; - Small leak in the hydraulic pipeline will be fatal to the transfer of
power; - Hydraulic drive can’t be employed in cases where an accurate
relation must be maintained between coordinated motions; - The occurrence of slip in hydraulic transmission drive has the
disadvantages where it is desired to maintain a uniform rate of
traverse; and - Speed of movement sometimes varies in viscosity of the oil with
change in temperature.
Applications of hydraulic drive system
- Brakes on tractor wheel
- Power stirring for tractors and self-propelled equipment
- Pushing and pulling equipment component
- Raising and lowering attachment of field equipment (plows and
harrows, combine headers, etc.) - Controlling the depth of tillage such as chisel and subsoiler, etc.
Draws the oil from the reservoir and sends
it to the control valve under high pressure. It uses either gear
pump, plunger pump, vane pump, or screw pump. Gear pump
is widely used in tractors because it can flow bigger amount of
oil compared with other pumps and oil pressure can be varied
from 150 to 200 kg/m2. It is operated by the transmission drive
of the engine
Hydraulic Pump
Hydraulic cylinder conveys
the oil to the piston, which raises the lifting arm, to cause it to
operate.
Hydraulic Cylinder and Piston
Contains the oil used in the hydraulic drive
system.
Hydraulic Tank or Reservoir
Controls the rate of flow of the oil
Control Valve
Directs the oil to the tank when there is over
pressure in the system.
Safety Valve
Delivers the oil from the pump to the
hydraulic cylinder and back to the reservoir.
Hose Pipe and Fittings
Raises or lowers the attached implement.
Lifting Arms
In an ______, the pump is always working, moving oil through
the pipes without building up pressure. Both the inlet to the pump
and the return valve are hooked up to a hydraulic reservoir.
Open hydraulic system
These are also called “open center” systems, because of the open
central path of the control valve when it is neutral. In this case,
hydraulic fluid returns to the reservoir. The fluid coming from the
pump goes to the device and then returns to the reservoir.
Open hydraulic system
