Care of Recoil Mechanism.
(Chief Mechanic Only)
Caution.—Never remove piston rod nut, as piston is under pressure and would pull piston rod into cylinder.
The recoil apparatus proper cannot be dismounted.
If properly taken care of the recoil mechanism will not go wrong for years; but if neglected, its destruction is only a matter of very little firing.
The position of the gauge finger is the index as to whether or not the recoil is being properly absorbed.
The joints are not absolutely tight, the slight leakage which takes place during fire or even when gun is at rest is not important.
In normal firing conditions the recoil apparatus contains a slightly greater quantity of oil than absolutely necessary; this quantity is called the “reserve.” When the reserve is exhausted any loss is liable to reduce the quantity strictly necessary. The loss may prevent the gun from fully returning to battery when firing.
The amount of reserve is indicated by the position of the gauge.
No reserve: The gauge finger is down deep in its recess.
Full reserve: The end of the gauge finger is level with the gauge index.
Excess reserve: The gauge finger projects beyond the index.
No firing should be done with an excess reserve.
The gauge finger should be between the index and ⅛ inch below the index.
It is the duty of the Chief Mechanic to see that the gauge finger is in the proper position before firing.
It is the duty of the Executive and the Chief of Section to see that the gauge finger is in the proper position during fire; if it moves from this position the Chief Mechanic will be called to make the proper adjustments.
When the gauge finger has been brought to the proper position there are only two conditions which call for tampering with recoil apparatus.
1. The gun goes into battery too slowly, or has to be pushed in.
In this case the gauge finger will usually be found too deep in its seat, and the pump will have to be used. If the gauge is in the proper position look at the slides. Either they will be found dirty or bits of the wiper may be nicked off. In the latter case the gun can be fired without the wiper.
2. The gun jumps badly. In this case the gauge finger will generally be found beyond the index. When this is the case the oil extractor must be used until the gauge finger is in the proper position.
If after cleaning slides, putting gun in abatage and adjusting gauge finger, the gun still jumps badly—complete draining of the reserve and refilling will frequently remedy the trouble.