Identify the Compound of the Hydraulic System shown in the figure. Describe the operation of the system. Draw an equivalent electrical circuit to the hydraulic system shown in the figure.

Here are the answers to the questions based on the provided hydraulic circuit diagram.

a) Identify the Components of the Hydraulic System:

1. Reservoir/Tank: Stores hydraulic fluid and allows for heat dissipation and contaminant settling.
2. Double-acting cylinder: An actuator that converts hydraulic energy into linear mechanical motion in both extension and retraction directions.
3. 4/2-way Directional Control Valve (DCV): A valve with 4 ports and 2 positions, actuated by a manual lever and returned by a spring. It directs fluid flow to control the direction of the double-acting cylinder.
4. Flow Control Valve (Throttle Valve): A valve that regulates the flow rate of hydraulic fluid, thereby controlling the speed of the double-acting cylinder.
5. Hydraulic Pump (Fixed Displacement): Converts mechanical energy from the motor into hydraulic energy by delivering a constant volume of fluid per revolution.
6. Electric Motor: Provides mechanical power to drive the hydraulic pump.
7. Pressure Relief Valve: A safety valve that protects the system from overpressure by diverting excess fluid back to the reservoir when the system pressure exceeds a preset limit.
8. Filter: Removes solid contaminants from the hydraulic fluid to protect components and maintain system cleanliness.
9. Single-acting cylinders (x2): Actuators that produce linear mechanical motion in one direction (extension) when pressurized fluid is supplied, and return to their initial position by means of an internal spring when pressure is released.

b) Describe the Operation of the System:

The system operates as follows:

• Power Generation: The electric motor drives the fixed displacement hydraulic pump, which draws hydraulic fluid from the reservoir through the filter. The pump then delivers pressurized fluid to the system.
• Pressure Regulation: The pressure relief valve is connected in parallel with the pump. It ensures that the system pressure does not exceed a safe maximum limit. If the pressure builds up too high, the valve opens, diverting excess fluid back to the reservoir, thus protecting the pump and other components.
• Single-Acting Cylinder Actuation: When the pump is running and supplying pressurized fluid, the two single-acting cylinders extend. When the pressure is released (e.g., if the pump stops or fluid is diverted elsewhere), their internal springs retract them.
• Double-Acting Cylinder Control: The 4/2-way directional control valve (DCV) controls the movement of the double-acting cylinder.
  • In its initial (spring-returned) position, the DCV directs pressurized fluid to one port of the double-acting cylinder, causing it to extend (or retract, depending on the connection). Fluid from the other side of the cylinder returns to the reservoir.
  • When the manual lever of the DCV is actuated, the valve shifts to its second position, reversing the flow. Pressurized fluid is now directed to the other port of the double-acting cylinder, causing it to retract (or extend).
  • The flow control valve, placed in the line to the double-acting cylinder, regulates the speed of the cylinder's movement by restricting the flow rate of the hydraulic fluid.

c) Draw an Equivalent Electrical Circuit to the Hydraulic System:

This ladder diagram represents the functional equivalence of the hydraulic system, using electrical components for control and indication.

\begin{array}{ll} \text{L1} & \text{L2 (24V DC)} \\ \text{|} & \text{|} \\ \text{---[PB2]---+---[PB1]---+---[KM1]---} & \text{Rung 1: Pump Motor Start/Stop Control} \\ \text{ NC |} & \text{ NO | Coil} \\ \text{ +---[KM1]---+} & \text{ NO} \\ \text{ } & \text{} \\ \text{---[KM1]---[L_{SA1\_Extend}]---} & \text{Rung 2: Single-Acting Cylinder 1 Extended Indicator} \\ \text{ NO Light} & \text{} \\ \text{ } & \text{} \\ \text{---[KM1]---[L_{SA2\_Extend}]---} & \text{Rung 3: Single-Acting Cylinder 2 Extended Indicator} \\ \text{ NO Light} & \text{} \\ \text{ } & \text{} \\ \text{---[SS1\_Extend]---[K1]---} & \text{Rung 4: Double-Acting Cylinder Extend Logic} \\ \text{ NO Coil} & \text{} \\ \text{ } & \text{} \\ \text{---[SS1\_Retract]---[K2]---} & \text{Rung 5: Double-Acting Cylinder Retract Logic} \\ \text{ NO Coil} & \text{} \\ \text{ } & \text{} \\ \text{---[K1]---[L_{DA\_Extend}]---} & \text{Rung 6: Double-Acting Cylinder Extended Indicator} \\ \text{ NO Light} & \text{} \\ \text{ } & \text{} \\ \text{---[K2]---[L_{DA\_Retract}]---} & \text{Rung 7: Double-Acting Cylinder Retracted Indicator} \\ \text{ NO Light} & \text{} \\ \text{|} & \text{|} \\ \text{-----------------------------------------------------------------------------------} & \text{0V DC} \end{array}

Explanation of Electrical Components:

• PB1 (Start Pushbutton - Normally Open): Initiates the pump motor operation.
• PB2 (Stop Pushbutton - Normally Closed): Stops the pump motor operation.
• KM1 (Motor Contactor Coil): Represents the pump motor being active. Its auxiliary contact (KM1 NO) provides latching for continuous operation.
• L_SA1_Extend, L_SA2_Extend (Lights): Indicate that the single-acting cylinders are extended, which occurs when the pump (KM1) is active.
• SS1_Extend (Selector Switch Contact - Normally Open): Represents the manual lever of the 4/2 DCV being actuated to the "extend" position for the double-acting cylinder.
• SS1_Retract (Selector Switch Contact - Normally Open): Represents the manual lever of the 4/2 DCV being actuated to the "retract" position for the double-acting cylinder. (SS1_Extend and SS1_Retract are contacts of a single 2-position selector switch, ensuring only one is active at a time).
• K1 (Relay Coil): Energized when the selector switch is in the "extend" position, representing the DCV directing fluid for extension.
• K2 (Relay Coil): Energized when the selector switch is in the "retract" position, representing the DCV directing fluid for retraction.
• L_DA_Extend (Light): Indicates that the double-acting cylinder is extending.
• L_DA_Retract (Light): Indicates that the double-acting cylinder is retracting.