Husco Split Spool Valve Operation02

Lie Li ebhe bh err Minin in ing g Equ Equip ipment ment Co. Co. Produc roductt Support Division HUSCO SPLIT SPOOL SYSTEM

Liebherr Mining Equip. Co 4100 Chest nu t Ave. Newpo Newpo rt News, VA. 23607

Technical Technical Training Training Department Department Teleph one = 757-928-250 757-928-2503 3

The term split split spool describes the spool section of the the main valve. The spool section encloses two spools and its components. Each spool is equivalent to one-half the spool in a conventional valve. The spool operates in synchronization with or in opposition to its mate. Each section is basically two 2-position / 3-way diverting diverting valves. This feature feature allows control and circuit flexibility.

The hydraulic schematic section depicted above will be utilized to describe specific components and functions of the Husco Split Spool Valve.

2

The hydraulic schematic section depicted above will be utilized to describe specific components and functions of the Split Spool Pilot Valve and the Pilot Control Valve.

The Inlet Section of the Main Dump Control Valve consists of a Flow Control Valve, Main Relief Valve, Low Pressure Relief Valve, Load Check Valve, and an Anti-Void Poppet. Take note of this particular particular diagram depicting the Husco 6500 Series, which has two inlet sections to accommodate the T-282s dual pump system.

3

Hydraulic flow for the split spool system can range from 90 GPM to 500 GPM. The 500 GPM is possible by using the 6500s paralleled inlet section. Some of the working features of the Main Dump Control Valve are as follows: • •

•

Complete pressure control is provided by a main relief valve. The large capacity flow control in the inlet section of the split spool, allows a low neutral pressure drop. A great degree of mounting flexibility is possible, which allows the pilot valve to  be located as to simplify controls and minimize line connections.

The Pilot Spool Valve is spring centered to the neutral position. The center passage is open and pilot flow from the main valve is unobstructed. As depicted here, the Pilot Spool Valve is actuated by a Pilot Control Valve. When the Pilot Control Valve directs flow to either end of the Split Spool, this will overcome the spring bias, and the flow control poppet opens and the pump flow is directed to the outlet.

4

Main Dump Valve Component Descriptions and Operations:

1. INLET = the port connection(s) for the system pump lines. 2. OUTLET = the port connection for the line(s) that directs return flow to the reservoir.

5

3. HIGH PRESSURE CORE = the passage which is common to the inlet section and the spool section of the main valve and directs pump flow to the spool sections. 4. DRAIN PASSAGE = the passage which allows portions of the surface area  between main valve sections to bleed-off directly to the outlet.

5. FLOW CONTROL = the inlet section component between the inlet and outlet ports. 6

5. MAIN RELIEF VALVE = the element located inside of the flow control poppet. It is a pilot operated (compound) relief valve, and has the capacity to limit the working pressure at full pump flow. 6. LOW PRESSURE RELIEF VALVE = the assembly located between the low  pressure core and the outlet, and provides a controlled back pressure in the low  pressure core when oil is returning from an actuator.

7

7. LOAD CHECK POPPET = the check valve that allows free flow from the inlet to the high pressure core and prevents flow from the high pressure core to the inlet. 8. ANTI-VOID POPPET = the check valve that allows free flow from the low  pressure core and prevents flow from the high pressure core from entering the low  pressure core.

8

9. PILOT SUPPLY ORIFICE = the orifice that is located between the inlet and the spring side of the flow control valve. It is in conjunction with the flow control spring, which regulates the amount of pilot flow to the pilot valve. 10. PILOT SUPPLY PORT = the port connection for directing flow from the pilot supply orifice to the pilot valve inlet. (See drawings above and below for reference)

9

11. FLOW CONTROL or DAMPENING POPPET = this is an orifice / check valve arrangement located between the pilot supply orifice and the spring side of the flow control. This arrangement regulates the filling or exhausting of the volume of oil behind the flow control. The orifice slows the movement of the flow control and prevents sudden changes in the direction of the pump flow, and thereby reduces shocks or surges. 12. WORK PORT or WORKING PORT = the port connection on the main valve spool section for a working line to be connected to one side of an actuator.

10

13. LONG HOLE = this term relates to the cross drilled hole in the spool section, which covers and provides a passage for flow from the low pressure core to its corresponding main spool. 14. MAIN SPOOL = There are one main spool for each work port and they are spring  biased at both ends. This is to block the work port from the high and low pressure cores when there is no flow through the spool cross-holes. When there is flow from the pilot valve to the main valve work port (through the cross-holes) a  positive differential pressure at the top of the spool will overcome the bottom spring bias and the spool will overcome the top spring bias and the spool will shift to connect the work port to the low pressure core.

11

15. RESTRICTOR POPPETS = these check valves are located in the main spools and are identified as DAMPENING POPPETS in the above diagram. They permit free flow from the work port to the pilot port and restrict flow from the pilot port to the work port. They are also used to control spool response and / or spool movement during void conditions.

16. PILOT VALVE INLET SECTION = the port connection for receiving pilot flow from the main valve pilot supply port. 17. PILOT VALVE OUTLET = connection for return to tank.

12

18. CENTER PASSAGE = the passage that directs pilot flow from the inlet to the outlet of the pilot valve when the spool is centered or in the float position. 19. BRIDGE CORE = this passage directs flow from the center passage to a control  port when the pilot valve spool is shifted.

20. PILOT SPOOL = the element in the system which is controlled directly by the operator of the unit. The pilot spool transforms the small pilot flow from the main valve into control signals which cause the main valve to direct the large working flow. 21. LOAD CHECK = the valve that allows free flow from the center passage to the  bridge core and prevents flow from the bridge core to the center passage. 22. SOLENOID VALVES = located on the pilot control valve, which when activated  by an operators selector will shift the flow of pilot pressure to the Split Spool Pilot Valve.

13

H1

H3