Mortar adaptor

A Mortar adapter intended to be received in the barrel of a mortar. The adapter includes a projectile firing tube and a breech region (2), wherein the projectile firing tube is intended to accommodate a practice projectile of smaller caliber than the caliber of the mortar barrel. The projectile is brought to a firing and locked state automatically as the projectile is inserted into the mortar adapter. There is provided a safety facility, which includes a breech block (7, 9) which is intended to be inserted into the adapter through the agency of a guide means (4, 5) which extends transversely to the longitudinal axis of the cylindrical breech (2) and when fully inserted forms the bottom of the breech. The measurements of the breech block in the insertion direction are such that at least one end (13, 14) of the breech block will touch the mantle line of the adapter (1) in the inserted position while the other end will lie within the adapter, so as to enable the adapter to be inserted freely in the mortar barrel (16) when the breech block ( 7, 9) is fully inserted. The breech block has a firing pin (15) which is so positioned that when the breech block (7, 9) is inserted, the firing pin (15) will lie centrally in register with the firing pin (22) of the mortar, so that the mortar firing pin is able to strike the firing pin (15), which in turn strikes the detonator of the practice projectile of smaller caliber inserted in the adapter.

The present invention relates to a mortar adapter which has the form of a 
dummy mortar shell or projectile and which is intended to fit the barrel 
of a standard mortar. The adapter has a practice missile launching tube 
and a practice missile breech position and can be loaded with a practice 
projectile whose caliber is smaller than the caliber of the mortar barrel. 
The object of the present invention is to provide a mortar adapter which 
can be used in mortar practice and which will accommodate a practice 
projectile in a manner such that as the practice projectile is inserted in 
the mortar adapter, a safety device will be brought automatically from an 
active safe state to a released and locked state when the adapter is 
inserted into the mortar barrel. 
The object is achieved in that the safety function operates automatically 
and has the characteristics features set forth in the characterizing 
clause of the following Claims.

FIG. 1 is thus a longitudinal sectional view of the mortar adapter, the 
largest dimension of which corresponds to the caliber of the mortar 
barrel. The rear end of the mortar adapter is the upper end of the 
illustrated adapter in FIG. 1, and it is thus this end of the adapter that 
is inserted to the bottom position in the mortar. The mortar adapter has a 
centre bore 2 which forms the projectile breech position, i.e. the 
position of the practice projectile when located in its firing position in 
the mortar. The bottom end of the illustrated mortar adapter, i.e. the end 
which faces upwards in the mortar barrel, is provided with an attachment 
region 3 for accommodating the launching tube which serves as a practice 
projectile aiming or sighting tube. When firing a practice projectile with 
the aid of the mortar adapter, the adapter is first loaded with the 
practice projectile, placing the projectile in its breech position. The 
bottom of the breech is formed by an end-closure piece, hereinafter called 
the breech block, (not shown in FIG. 1), which is inserted into grooves 4 
and 5 which extend transversely to the longitudinal axis of the breech and 
from one side of the mortar and beyond the other side of the breech, 
without passing through the other side of the mortar adapter. 
FIG. 2 is a cross-sectional view taken on the line II--II in FIG. 1 and 
illustrates the cylindrical bore 2 of the breech. 
The grooves 4 and 5 are shown to extend from the right side of the mortar 
adapter as shown in FIG. 2, and to extend beyond the left side of the 
breach region. As will be seen from the Figure, the grooves have a 
semi-circular configuration after passing the symmetry line 6--6. A breech 
block is now inserted into the grooves 4 and 5, from the right side of the 
FIG. 2 illustration. The breech block is shown in top view in FIG. 3 and 
in side view in FIG. 4. The breech block has two tiers or levels. A first 
tier 7 has a width which corresponds to the diameter of the breech 2. As 
will be seen from FIG. 3, the left end of the breech block tier 7 is 
semi-circular in shape, as shown at 8. The other end of the tier 7 is 
straight. The other tier, or level, 9 is broader than the tier 7 and has 
edge regions 10 and 11 which fit into respective grooves 4 and 5. The 
inner end of the tier 7 is also semi-circular, as shown by the arc 12. The 
other edge is cut transversely in line with the edge of the tier 7. The 
right end edge of the breech block illustrated in FIGS. 3 and 4 is 
provided with a guide shoulder 13. The guide shoulder 13 has an oblique 
outer end which functions as a guide surface as the breech block or 
end-closure piece is pushed into the mortar adapter, i.e. into the grooves 
4 and 5, by sliding against the inner surface of the barrel. This will be 
described in more detail further on. The breech block includes a striking 
pin mechanism 15, which is only shown schematically in the drawings and 
which is activated by the conventional mortar firing pin mechanism when 
the breech block is in a practice projectile firing position, i.e. a 
safety release position. 
FIG. 5 illustrates the breech block 7 inserted slightly into the mortar 
adapter, although the adapter has not yet been inserted fully into the 
mortar barrel, but lies in front of the mouth of the barrel. The barrel is 
referenced 16. FIG. 5 also illustrates a breech block counterpressure 
mechanism or anvil, generally referenced 17. The counterpressure mechanism 
is located in the mortar adapter on the same level as the grooves 4 and 5 
and at the bottom thereof. As will be seen, the grooves 4 and 5 are 
terminated at their respective bottoms in a semi-circular shape 18 
corresponding to the semi-circular shape 12 of the breech block. The 
counterpressure mechanism 17 is thus placed in the left end of the grooves 
4 and 5. This counterpressure mechanism includes a pin 19 which acts 
against a pressure spring 20 and has an attachment in the bottom of a bore 
21 accommodating the pin 19. The pin 19 is thus able to move backwards and 
forwards in the bore 21, against the force exerted by the spring 20. 
FIG. 6 illustrates the next position of the breech block, where the 
practice projectile is made safe against firing. Thus, in this position, 
the practice projectile is located in the breech position, or 
alternatively a projectile propellant is placed in the breech position 
with the practice projectile placed in front of the propellant. Whichever 
case applies, the inner end of the propellant or the practice projectile, 
i.e. the end containing the fuse, rests against the upper side of the 
breech block 7. Since the practice projectile is centered in the breech, 
the detonator of the practice projectile will be located in the centre 22 
of the breech. However, the breech block striking pin 15 is located on one 
side of the centre position 22, meaning that the detonator of the practice 
projectile cannot be activated, or alternatively the detonator of the 
propellant cannot be activated. For the sake of simplicity, the practice 
projectile will be considered to include a propellant in the following, 
and consequently no difference will now be made between a propellant and a 
practice projectile. As shown in FIG. 6, in this stage of operations, the 
breech block has not been inserted into the mortar adapter to an extent 
such that the guide shoulder passes free from the inner surface of the 
barrel 16. The mortar adapter thus still lies outside the mouth of the 
barrel. Neither is the inner end of the breech block affected by the 
counterpressure mechanism 17. 
FIG. 7 illustrates the breech block 7 in a locked and firing position. In 
this stage, the breech block 7 has been inserted into the mortar adapter 
to an extent at which the guide shoulder 13 is in engagement with the 
inner surface of the barrel and in which the left end of the breech block 
presses the pin 19 against the force exerted by the spring 20. The mortar 
adapter is now inserted in the barrel and the pin 19 urges the breech 
block to the right through the action of the spring 20, so that the breech 
block 13 will now lie against the inner surface of the barrel. The breech 
block is therefore locked and located in its firing position, i.e. the 
firing pin 15 lies in the centre 22 of the barrel. When the mortar 
adapter, together with practice projectile and propellant, is dropped down 
in the barrel, the mortar firing mechanism will immediately activate the 
breech block firing pin and the propellant will be fired, so as to propel 
the practice projectile from the firing tube of the mortar adapter and 
thus from the mortar. The mortar adapter, on the other hand, remains in 
the mortar barrel. Immediately the mortar adapter is removed from the 
barrel, the breech block returns automatically to the position illustrated 
in FIG. 6, i.e. a safe position in which the mortar adapter can again be 
loaded with a propellant and practice projectile. 
It should be noted that the mechanism described together with the breech 
block and grooves in the mortar adapter is referred to as a wedge 
mechanism in use with conventional guns. It should also be noticed that 
the mortar adapter has a configuration and weight which coincides with the 
shape and weight of standard conventional mortar ammunition. 
It is emphasized that the mortar adapter (also called dummy mortar shell) 
is dropped into the mortar barrel and that the projectile propellant is 
fired when the mortar adapter reaches the firing position at the bottom of 
the mortar barrel, therewith propelling the practice projectile from the 
barrel.