| CPC B25C 1/043 (2013.01) [B25D 9/20 (2013.01); F15B 13/027 (2013.01); F15B 15/20 (2013.01); F16K 31/163 (2013.01); B25C 1/047 (2013.01); B25D 9/08 (2013.01); B25D 2250/181 (2013.01); F41B 11/72 (2013.01)] | 19 Claims |

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1. An actuation trigger for a device, comprising:
a dose chamber to hold a charge of high pressure working fluid, received from a high pressure source;
a dose valve biased closed to seal the dose chamber off from a working chamber and hold the charge in the dose chamber;
a hammer operated by a piston with a driven chamber on a first side of the piston, and a trigger chamber on a second side of the piston, sealed from the first side, the driven chamber receiving the high pressure working fluid directly or indirectly from the high pressure source; and
a trigger valve to selectively supply the high pressure working fluid to the trigger chamber, or to release the high pressure working fluid from the trigger chamber,
wherein, when the hammer has the high pressure working fluid in both the driven chamber and the trigger chamber, the hammer is held by a force imbalance in a first position, and when the high pressure working fluid is released from the trigger chamber, the hammer is driven to or towards a second position towards the trigger chamber; and
wherein the hammer, when driven to or towards the second position, strikes the dose valve, unseating the dose valve to unseal the dose chamber and the working chamber thus allowing the charge to enter the working chamber to do work therein.
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