In-line fluid pump and shuttle valve therefor

A fluid pump comprising:

• first and second coaxially arranged hollow cylinders forming an annular chamber and having end walls enclosing said chamber;
• an annular piston received within and dimensioned for fitting sliding receipt along the annular chamber;
• at least one drive rod connected to the annular piston and extending through an opening;
• first and second ports in the inner cylinder wall located respectively at opposite ends of the chamber;
• inlet means interconnecting a source of pressurized fluid with one end of the inner hollow cylinder;
• outlet means interconnecting with the other end of the inner hollow cylinder;
• reciprocating drive means connected to the drive rod;
• and
• valving means located within the inner cylinder synchronized with the reciprocating movement of the drive rod to interconnect the port ahead of the moving annular piston to the outlet means and the port behind the moving annular piston to the inlet means, said valving means including first and second platelike members, a plurality of spaced hollow tubes extending through the platelike members and maintaining said members at a fixed spacing, and an open-ended pipe affixed to said first platelike member and providing fluid communication between the inlet means through said first platelike member to the space between said plurality of tubes.