The role of the main pressure limiter is to protect the pump from overpressure.
The pump generates a flow that must be directed at all times:
- To the hydraulic receivers.
- To the tank using a directional valve.
- To the tank using a pressure relief valve.
Relative pressure : the pressure read on the pressure gauges in the hydraulic circuits.
Atmospheric pressure : Pressure exerted by the air on the earth's surface (about 1 bar).
Absolute pressure: It is the addition of the relative pressure and the atmospheric pressure (total pressures).
The role of the pressure reducing valve is to protect a part of the hydraulic circuit by reducing the pressure.
Some examples:
- Protect the brake of a hydraulic motor.
- Provide reduced pressure to hydraulic joystick controls.
- Reduce the pressure of a control circuit.
The role of the pressure reducing valve is to protect a part of the hydraulic circuit by reducing the pressure.
Some examples:
- Protect the brake of a hydraulic motor.
- Provide reduced pressure to hydraulic joystick controls.
- Reduce the pressure of a control circuit.
In the hydraulic diagram, the pressure relief valve is located between the pump and the distributor.
The assembly is sandwiched between a manifold block and a directional valve. Four O-rings will seal between each slice and will be assembled with four screws
In hydraulic circuits, the same component can be called choke, flow restrictor or flow limiter.
The role of the flow limiter is to reduce the speed of the receivers (jacks or motors).
The specification states to size a hydraulic circuit to operate a press cylinder.
We have a double-acting cylinder with a length of 30cm. The diameter of the piston is 160mm and the diameter of the rod is 80mm.
The flow regulator keeps a constant flow regardless of the load of the receiver.
There are two types of flow regulator:
- 2-way flow regulator.
- 3-way flow regulator.
In hydraulics, the directional valve's role is to direct the oil towards the receivers. It can be "all or nothing" or proportional.
The pilot order can be:
- Electric.
- Mechanical by lever or cable.
- Hydraulic.
- Pneumatic.
There are 2 types of directional valves:
- A poppet valve: They have the distinction of being waterproof. On the other hand, their number of positions remain limited.
- With spools: They can be 3/2 - 4/3 - 6/3 ... On the other hand they are not waterproof.
The above directional valve is a Cetup type mounting (ISO standard).
It is mounted on a drilled block and assembled with 4 screws. The seal between the drilled block and the distributor is provided by 4 O-rings.
The directional valves make it possible to direct the oil towards the receivers.
We distinguish 2 large families
- Poppet: the advantage of this type of directional valve is to be sealed internally when closed.
- Spool : the advantage of this type of dispenser is to have a greater number of positions.
The loop circuit will be reserved for rotary movements (motors). In very rare cases to linear movements. (Marine for example).
Also called hydrostatic circuit, it is mainly found on mobile machines (public works, agriculture, forestry, marine, etc.)
The role of the jacks is to transform hydraulic energy into linear force.
There are 2 modes of action:
- Single acting cylinders.
- Double acting cylinders.
The relay is regularly used in on-board electrical installations. (Light vehicle, heavy goods vehicles, public works equipment, agricultural equipment, etc.
The relays separate the control circuits from the power circuits.
The 4/3 LS directional valve is progressive or proportional. The control can be manual, electric or hydraulic.
It is used in mobile applications (public works, agriculture, ports, etc.). It makes it possible to manage the speed of the receivers and to facilitate the operation of the machines.
The sensors make it possible, for example, to check the position or the presence of a piece.
The inductive sensor detects ferrous objects while the capacitive sensor detects any material.
These sensors are active sensors. They must be powered to work. These sensors must be checked with power.
Load Sensing pumps are present in mobile applications. They make it possible to reduce energy consumption by adapting the flow rate to the pressure required for the operation of the machine.
A control of the pumps makes it possible to carry out preventive measures, to reduce the failure rate and the costs. An HS pump can pollute the entire hydraulic circuit.
To control the efficiency of the pumps, it is necessary to install a flow meter and compare the theoretical flow with the flow measured under load.
Choosing valves with proportional control makes it possible to control accelerations and decelerations. This choice gives access to a wide range of settings
The PID regulator is an electronic card which makes it possible to perform mathematical calculations on signals in order to adjust the control signal to the requested setpoint.
The hydraulic coupling has 2 ends:
• Installation: The fitting is screwed onto a drilled block or onto a hydraulic component.
• The adaptation: This is the part of the connection where the flexible or rigid hydraulic is screwed.
A vehicle 's charging circuit must be capable of supplying the electrical current needed to recharge the battery and supply all of the vehicle's consumers
The cost of filtration is a significant budget for maintenance. Good filtration extends the life of hydraulic components and reduces breakdowns, but you don't need over-quality.