Dual pump operation of coin-operated washing system

Claim 1

In a high pressure liquid pumping system having means for selecting multiple output pressures and capacities and comprising: (a) motor means having an output shaft delivering energy at a certain predetermined rotational rate; (b) first and second fluid pumps, each having an input drive shaft and with the fluid inlet of each being coupled to a common source of liquid, conduit means coupling the inlet of said first fluid pump to the inlet of said second fluid pump, and with the outlet of each fluid pump being coupled together to a common discharge line, and with said discharge line having means for providing an intermittent output from said pumping system; (c) first and second drive means coupling said motor means to said input drive shafts of said first and second fluid pumps respectively, with said first drive means being normally drivably coupled to said drive shaft of said first fluid pump, and with said second drive means being normally disengaged from driving said drive shaft of said second fluid pump and having an electrical selector switch means for selectively and electromechanically coupling said second drive means to said drive shaft of said second fluid pump, and (d) bypass means including a bypass conduit having an automatic, pressure-operated unloader valve interposed therealong coupling the output of said second fluid pump to the inlet thereof, with the fluid flow through said bypass conduit being controlled by said automatic, pressure-operated unloader valve.