BAIR.D &TATLOCK (LONDON) LTD. 



"Geryk" Patent Vacuum Pumps. 



INTRODUCTION. 



The " Geryk " Vacuum Pump is now so well known that it is unnecessary to enlarge upon its merits. 

 It combines the advantages of great simplicity with the power of obtaining a very high vacuum. 

 It can be made in any sizes up to 100 or more cubic feet capacity per minute. 

 The larger pumps give a vacuum in every respect equal to that obtained by the smaller pumps. 

 Its uniform efficiency is not impaired by constant running. 



Section of Barrel. 



DESCRIPTION. 



A. Suction Pipe. 



B. Air port into cylinder above piston. 



C. Piston bucket leather, an easy fit in cylinder, and kept up to walls of cylinder by pressure of oil in annular 

 space (D). 



E. Piston valve which moves when commencing to exhaust only, and is quite inactive when vacuum is 

 within about J in. 



F. Air pipe to relieve piston on first few strokes. 



G. A collar through which piston rod passes fieely. 



I. A hydraulic collar to make joint with piston rod, the flange or face of which covers joint of (G) with cover 

 (H), thus forming a frictionless equivalent of a stuffing-box and a delivery valve combined. When piston is at 

 bottom of stroke there is a perfectly free opening from (A) to (B). As the piston rises the port (B) is cut off and the 

 cylinder full of air irresistibly carried up to the outlet valve (G). No air can by any possibility get back past 

 the piston as it is covered with oil. As the piston continues to rise and the pressure upon it increases, so the 

 bucket leather is forced more tightly against the walls of the cylinder. 



CROSS STREET HATTQN GARDEN, E-C 



706 



