| 摘要 |
A first piston 20 is cocked by applying pressure to a chamber 17 in the front end of a cylinder 10, which attendantly compresses a first spring 70. Upon subsequently releasing a trigger latch 82, the spring 70 drives an injection needle 31 carried by the rod 22 of the piston into a tree trunk. Pressure is next applied to a space 45 behind a second piston 40 slideable within the first piston skirt, which zero volumes a chamber 21 between the two pistons and compresses a second spring 71. The space 45 is then vented, whereupon the spring 71 separates the two piston heads to vacuum fill the reestablished chamber 21 with a vascular treatment liquid for trees. Finally, the space 45 is re-pressurized to force the liquid into the tree through the inserted needle.
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