Graphical symbols
The key control device in modern heavy and agricultural equipment is the joystick.Although the primary function of a modern joystick is to drive input commands or messages, it is also an output device, enabling the management system to provide real-time, tactile feedback to the machine operator. Today’s joysticks are also digital devices and although the general operating principle of a digital joystick is similar to its analog predecessor, the outputs are delivered at higher speeds and much greater precision. An electronic control unit (ECU) is a modular housing containing a microprocessor, data retention media, and, usually, an output or switching apparatus. The ECU is a system controller. It is usually mounted close to the components it manages, although in heavy-equipment applications, a requirement is to protect the devices from dirt. Today’s equipment uses several system controllers to manage the engine, transmissions, hydraulics, climate control, and just about everything else. To facilitate this communication, each controller is connected to a communications network known as a data bus.
Summary
The key control device in modern heavy and agricultural equipment is the joystick.Although the primary function of a modern joystick is to drive input commands or messages, it is also an output device, enabling the management system to provide real-time, tactile feedback to the machine operator. Today’s joysticks are also digital devices and although the general operating principle of a digital joystick is similar to its analog predecessor, the outputs are delivered at higher speeds and much greater precision. An electronic control unit (ECU) is a modular housing containing a microprocessor, data retention media, and, usually, an output or switching apparatus. The ECU is a system controller. It is usually mounted close to the components it manages, although in heavy-equipment applications, a requirement is to protect the devices from dirt. Today’s equipment uses several system controllers to manage the engine, transmissions, hydraulics, climate control, and just about everything else. To facilitate this communication, each controller is connected to a communications network known as a data bus.
Things to Remember
- The key control device in modern heavy and agricultural equipment is the joystick.
- Although the primary function of a modern joystick is to drive input commands or messages, it is also an output device, enabling the management system to provide real-time, tactile feedback to the machine operator.
- Today’s joysticks are also digital devices and although the general operating principle of a digital joystick is similar to its analog predecessor, the outputs are delivered at higher speeds and much greater precision.
- An electronic control unit (ECU) is a modular housing containing a microprocessor, data retention media, and, usually, an output or switching apparatus. The ECU is a system controller. It is usually mounted close to the components it manages, although in heavy-equipment applications, a requirement is to protect the devices from dirt.
- Today’s equipment uses several system controllers to manage the engine, transmissions, hydraulics, climate control, and just about everything else.
- To facilitate this communication, each controller is connected to a communications network known as a data bus.
MCQs
No MCQs found.
Subjective Questions
No subjective questions found.
Videos
No videos found.
Graphical symbols
JOYSTICKS
The key control device in modern heavy and agricultural equipment is the joystick. The first generation of joysticks were analog input-only devices. That has changed. Although the primary function of a modern joystick is to drive input commands or messages, it is also an output device, enabling the management system to provide real-time, tactile feedback to the machine operator. Today’s joysticks are also digital devices and although the general operating principle of a digital joystick is similar to its analog predecessor, the outputs are delivered at higher speeds and much greater precision.
Engine and System Controllers
Onboard vehicle computers are referred to as engine/ electronic control modules (ECMs) (SAE recommended acronym for engine controllers) or engine/ electronic control units (ECUs) (SAE recommended acronym for all other chassis system controllers).
ELECTRONIC CONTROL UNIT
An electronic control unit (ECU) is a modular housing containing a microprocessor, data retention media, and, usually, an output or switching apparatus. The ECU is a system controller. It is usually mounted close to the components it manages, although in heavy-equipment applications, a requirement is to protect the devices from dirt. Figure 19-1 shows ECUs mounted behind the firewall on a piece of equipment.
Today’s equipment uses several system controllers to manage the engine, transmissions, hydraulics, climate control, and just about everything else. All these ECUs need to communicate with each other. To facilitate this communication, each controller is connected to a communications network known as a data bus. The data bus may either be hard wire (J1939 uses a two-wire network channel) or optical.
Graphical symbols of hydraulic / pneumatic elements and equipment
| Symbol | Designation | Explanation |
| Supply System | ||
|
| Air compressor | One direction of rotation only with constant displacement volume |
|
| Air receiver (Reservoir) | Compressed air from the compressor is stored and diverted to the system when required |
|
| Hydraulic pump | One direction and two direction of rotation with constant displacement volume |
|
| One direction and two direction of rotation with variable displacement | |
| Rotary Actuators | ||
|
| Pneumatic motor | One direction and two direction of rotation with constant displacement volume |
|
| One direction and two direction of rotation with variable displacement | |
|
| Hydraulic motor | One direction and two direction of rotation with constant displacement volume |
|
| One direction and two direction of rotation with variable displacement | |
| Service Units | ||
|
| Air filter | This device is a combination of filter and water separator |
 | Dryer | For drying the air |
|
| Lubricator | For lubrication of connected devices, small amount of oil is added to the air flowing through this device |
|
| Regulator | To regulate air pressure |
|
| FRL unit | Combined filter, regulator and lubricator system |
| Direction Control Valves (DCVs) | ||
|
| 2/2 way valve | Two closed ports in the closed neutral position and flow during actuated position |
|
| 3/2 way valve | In the first position flow takes place to the cylinder In the second position flow takes out of the cylinder to the exhaust (Single acting cylinder) |
 | 4/2 way valve | For double acting cylinder all the ports are open |
|
| 4/3 way valve | Two open positions and one closed neutral position |
|
| 5/2 way valve | Two open positions with two exhaust ports |
| Non Return Valves | ||
|
| Check valves | Allows flow in one direction and blocks flow in other direction |
|
| Spring loaded check valves | |
|
| Shuttle/OR valve | When any one of the input is given the output is produced |
|
| AND valve | Only when both the inputs are given output is produced |
|
| Quick exhaust valve | For quick exhaust of air to cause rapid extension/ retraction of cylinder |
| Flow control valves | ||
|
| Flow control valve | To allow controlled flow |
|
| Flow control valve with one way adjustment | To allow controlled flow in one direction and free flow in other |
| Pressure Control Valves | ||
|
| Pressure relieving valve | Non relieving type |
|
| Relieving type with overload being vented out | |
|
| Pressure reducing valve | Maintains the reduced pressure at specified location in hydraulic system |
|
| Unloading valve | Allows pump to build pressure to an adjustable pressure setting and then allow it to be discharged to tank |
|
| Counter balance valve | Controls the movement of vertical hydraulic cylinder and prevents its descend due to external load weight |
| Actuators | ||
|
| Single acting cylinder | Spring loaded cylinder with retraction taking place by spring force |
|
| Double acting cylinder | Both extension and retraction by pneumatic/hydraulic force |
Lesson
Electronic Component and their functions
Subject
Mechanical Engineering
Grade
Engineering
Recent Notes
No recent notes.
Related Notes
No related notes.