A rod actuator particularly for a mastic gun comprises wear compensation and pressure relief. The wear compensation is effected by a biased catch plate. The catch plate is released from the rod in the actuator by a sleeve transmitting a releasing force applied to a brake plate through to the catch plate. The pressure relief is provided also by the sleeve riding on the rod such that when the trigger is released the rod is able to retreat by a limited amount defined by the movement of the release plate between a released and engaged relationship with the rod.
1. An actuator for advancing a rod comprising:
a stock defining a channel for the rod;
a catch member engageable with the rod;
a trigger member for moving the catch member to engage and advance the rod in a first direction;
a release member engageable with the rod to prevent the rod from retreating in a second direction substantially opposite the first direction; and
a sleeve on the rod, extending between the release member and the catch member for transmitting a relieving force applied to the release member to the catch member to urge the catch member from engagement with the rod, thereby enabling the rod to be moveable in the second direction;
wherein the sleeve is held to move with the release member and is arranged to move with the rod such that the release member moves with the rod to and from an engaged relationship with the rod.
2. The actuator of claim 1 , wherein the release member is arranged to move with the rod to an engaged attitude with respect to the rod as the rod is retreated, thereafter preventing further retreat of the rod.
3. The actuator of claim 1 , wherein the release member is arranged to move with the rod as the rod is initially advanced.
4. The actuator of claim 1 , wherein the release plate is arranged to be movable between a released and an engaged attitude with respect to the rod.
5. The actuator of claim 1 , wherein the catch member is a catch plate biased into an attitude of engagement with respect to the rod so that actuation of the trigger causes immediate movement of the catch member and the rod.
6. The actuator of claim 5 , wherein the release member is operable to release the rod and transmit its movement through the sleeve to move the catch plate to release the rod.
7. The actuator of claim 6 , wherein the release member is a release plate moveable between an engaged attitude and a released attitude with respect to the rod.
8. The actuator of claim 1 , wherein the actuator is operable in a mastic applicator.
9. An actuator for advancing a rod comprising:
a stock defining a channel for the rod;
a catch member engageable with the rod;
a trigger member for moving the catch member to engage and advance the rod in a first direction;
a release member engageable with the rod to prevent the rod from retreating in a second direction substantially opposite the first direction; and
a sleeve on the rod, extending between the release member and the catch member for transmitting a relieving force applied to the release member to the catch member to urge the catch member from engagement with the rod, thereby enabling the rod to be moveable in the second direction;
wherein the sleeve is held to move with the release member and is arranged to move with the rod such that the release member moves with the rod to and from an engaged relationship with the rod, wherein the sleeve is held to move with the release member by means of a jaw which engages a flange on one end of the sleeve and receives the release member within its body.