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A restarting device of a pump change-over valve in a pump is provided, in which the pump includes; a pump main body 1 and a change-over valve 2. The change-over valve 2 is provided with a pair of pressure chambers 31 and 32 formed at respective ends on the back face sides of a valve body 23. The dri

A restarting device of a pump change-over valve in a pump is provided, in which the pump includes; a pump main body 1 and a change-over valve 2. The change-over valve 2 is provided with a pair of pressure chambers 31 and 32 formed at respective ends on the back face sides of a valve body 23. The driving fluid is supplied into the chambers to induce a pressure difference to switch the direction of movement of the valve body 23. Also, the pump main body 1 is provided with a balancing valve 49 whose end portions 49A and 49B face driving chambers 4A and 5A, respectively. If the change-over valve 2 malfunctions and the pressures in the two driving chambers 4B and 5B are balanced, the balancing valve 49 is held in an intermediate position and will then induce a pressure difference between the two pressure chambers 31 and 32.

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A restarting device of a pump change-over valve in a pump is provided, in which the pump includes; a pump main body 1 and a change-over valve 2. The change-over valve 2 is provided with a pair of pressure chambers 31 and 32 formed at respective ends on the back face sides of a valve body 23. The dri

A restarting device of a pump change-over valve in a pump is provided, in which the pump includes; a pump main body 1 and a change-over valve 2. The change-over valve 2 is provided with a pair of pressure chambers 31 and 32 formed at respective ends on the back face sides of a valve body 23. The driving fluid is supplied into the chambers to induce a pressure difference to switch the direction of movement of the valve body 23. Also, the pump main body 1 is provided with a balancing valve 49 whose end portions 49A and 49B face driving chambers 4A and 5A, respectively. If the change-over valve 2 malfunctions and the pressures in the two driving chambers 4B and 5B are balanced, the balancing valve 49 is held in an intermediate position and will then induce a pressure difference between the two pressure chambers 31 and 32. el secured to said mandrel sealing member, said bottom bladder mandrel having a communication passage therethrough for fluidly connecting said liquid chamber to said inlet chamber; and a support member extending between said top and bottom mandrel inside said bladder, wherein said bladder being sealingly secured to said top bladder mandrel at one end and to said bottom bladder mandrel at the other end, and wherein said liquid chamber is enclosed within said flexible bladder. 2. The bladder-type fluid-actuated liquid pump as defined in claim 1, wherein said bottom bladder mandrel is removably secured to said mandrel sealing member. 3. The bladder-type fluid-actuated liquid pump as defined in claim 1, wherein said inlet check valve is removably secured to said bottom bladder mandrel. 4. The bladder-type fluid-actuated liquid pump as defined in claim 1, wherein said outlet check valve is disposed in said top cap. 5. The bladder-type fluid-actuated liquid pump as defined in claim 4, wherein said outlet check valve is disposed within said liquid outlet port in said top cap. 6. The bladder-type fluid-actuated liquid pump as defined in claim 4, wherein said outlet check valve includes a valve seat formed in said liquid outlet port of said top cap and a complementary valve closure member. 7. The bladder-type fluid-actuated liquid pump as defined in claim 6, wherein said valve closure member is a substantially spherical in shape. 8. The bladder-type fluid-actuated liquid pump as defined in claim 6, wherein said valve closure member is made of one of polytetrafluoroethylene and plastic material. 9. The bladder-type fluid-actuated liquid pump as defined in claim 1, wherein said inlet check valve includes a valve body secured to said bottom bladder mandrel, a valve seat formed in said valve body and a complementary valve closure member. 10. The bladder-type fluid-actuated liquid pump as defined in claim 9, wherein said valve closure member is a substantially spherical in shape. 11. The bladder-type fluid-actuated liquid pump as defined in claim 9, wherein said valve closure member is made of one of polytetrafluoroethylene and plastic material. 12. The bladder-type fluid-actuated liquid pump as defined in claim 1, wherein said inlet check valve and said outlet check valve are both ball-shaped check valves. 13. The bladder-type fluid-actuated liquid pump as defined in claim 1, wherein said bottom bladder mandrel has a substantially conical sealing surface sealingly engaging a substantially complementary conical sealing surface provided on said mandrel sealing member. 14. The bladder-type fluid-actuated liquid pump as defined in claim 1, wherein said bottom bladder mandrel is removably secured to said mandrel sealing member by means of a nut member threaded onto said bottom bladder mandrel. 15. The bladder-type fluid-actuated liquid pump as defined in claim 1, wherein said inlet check valve is secured to said bottom bladder mandrel. 16. The bladder-type fluid-actuated liquid pump as defined in claim 1, wherein said top bladder mandrel is removably secured to said top cap. 17. The bladder-type fluid-actuated liquid pump as defined in claim 1, further including a screen filter disposed adjacent to said intake opening to filter the liquid flowing therethrough. 18. The bladder-type fluid-actuated liquid pump as defined in claim 1, wherein said bladder having a central portion and opposite ends, and said central portion having a larger diameter than said ends. 19. The bladder-type fluid-actuated liquid pump as defined in claim 1, wherein said flexible bladder being made of polytetrafluoroethylene. 20. The bladder-type fluid-actuated liquid pump as defined in claim 1, wherein said tubular casing being made of plastic material. 21. The bladder-type fluid-actuated liquid pump as defined in claim 20, wherein said plastic material is polyvinyl chloride. 22. The bladder-type fluid-actuated liquid pump as defined in claim 1, wherein said support me