| 摘要 |
<p>The liquid reservoir tank of plant spraying equipment of the haversack type is pressurized by a pair of foot pumps worn by the operator under his shoes. Each pump comprises a resiliently compressible hollow cushion which is compressed by the operator's weight as he places the relevant foot on the ground and which expands when he lifts that foot from the ground, air being drawn into the cushion as it expands and being displaced from it into the tank as the cushion is compressed.</p> |
