bores is open the pump work chamber 16 communicates with the suction chamber 25 and neither can iadd either iaddend the pump work chamber 16 iadd can iaddend be filled from the suction chamber 25 nor can iadd or iaddend a return flow of the fuel from the pump work chamber 16 back to the suction chamber 25 can take place in fig2 and 3 four different stroke positions of the pump piston 12 are shown for the sake of explanation these positions only the pump piston 12 the cylinder bushing 11 and the control slide 14 are shown the stroke positions from left to right are as follows fig2 bottom dead center ut and supply onset fb and fig3 end of supply fe and top dead center ot in all four stroke positions of the piston ut fb fe and ot for the sake of easier comprehension of the ensuing explanation of the function the control slide 14 is shown in this same position while in the ut position a filling of the pump work chamber 16 takes place from the suction chamber 25 and the aperture 13 that is the recess 30 and from there via the upper control bore 28 and the blind bore 27 in the fb position both control bores 28 and 29 are blocked beyond this fb position for the rest of the compression stroke of the pump piston 12 fuel is delivered to the engine from the pump work chamber 16 beyond the fe position the end of supply is initiated that is the injection is interrupted by means of the lower control bore 29 cooperating with the.