US3143073A - Fluid pressure actuated time delay fuze - Google Patents

Description

I g- 4, 1964 J. R. J-ASSE; 3,143,073

FLUID ACTUATED TIME DELAY FUZE Filed March 8, 1962 I i B-Shee tS-Sheet '1 Aug. 4, 1964 J- R. JASSE.

FLUID PRESSURE ACTUATED TIME DELAY FUZE Filed March 8, 1962 2 Sheets-Sheet 2 I. W -I ll m dlllmillllV/ United States Patent France Filed Mar. 8, 1962, Ser. No. 178,484 Claims priority, application France Mar. 11 1961 6 Claims. ((Il. 102-856) The present invention relates to self-propelled projectiles adapted to be launched by means of an auxiliary charge contained in the launching or firing tube.

It is known to provide in the propelling gas ejection nozzle of such projectiles an ejectable obturating and igniting device which ignites with a certain time delay the propelling charge after which it is automatically ejected by the first gases under pressure produced by this charge.

A pyrotechnic relay housed in this obturating device can be ignited either by the launching charge or by a percussion igniting device Wholly housed in the obturating device.

In the case of ignition by the auxiliary launching charge, in the known arrangements it is the flames emanating from this launching charge which directly cause the ignition of a pyrotechnic time delay means which in turn ignites the relay. A serious drawback could arise in this arrangement when the pressure of the gases generated by the launching charge is high and reaches or exceeds for example 1,000 kg. per sq. crn., since in this case there is a danger of the ignited gases of the launching charges short-circuiting the time delay charge owing to their high pressure and causing a premature ignition of the relay and consequently of the propelling charge.

The object of the invention is to avoid this serious drawback and provide an improved ejectable obturating and igniting device for a self-propelled projectile adapted to be ignited by an auxiliary launching charge. This pyrotechnic time delay device, disposed at the rear of an igniting relay, is so arranged that there is provided behind said pyrotechnic delay an igniting device having a forward primer and a rear firing pin, the latter being carried by a piston movable in a fiuidtight manner in a cylinder which is formed in the body of the device and whose portion located at the rear of the piston communicates with the exterior of said body by way of at least one orifice.

In this arrangement, in the course of ignition of the auxiliary launching charge the resulting gases enter said cylinder behind the piston and cause the displacement of the latter forwardly of the projectile so that the firing pin strikes the primer; the gases of the primer in turn cause the ignition of the time delay and, through the medium of the latter, the ignition of the relay which thereafter ignites the projectile propelling charge, without it being possible for the high-pressure gases from the launching charge to enter the ejectable device beyond the piston which moves in a fiuidtight manner in the cylinder and therefore completely arrests these gases. Thus, no shortcircuiting of the pyrotechnic time delay by the gases can occur and, moreover, the gases of the primer are at a pressure which is much too low for such an incident to be caused by them. Any short-circuiting is therefore completely precluded.

According to another feature of the invention, the cylinder in which the piston moves is rearwardly extended beyond the orifice communicating with the exterior of the body so as to constitute a cavity into which the piston can withdraw under the effect of pressure due to the primer gases.

Consequently, any pressure due to these primer gases is avoided, since they are put in communication with the atmosphere by way of said orifice; therefore these gases are also quite incapable of short-circuiting the time delay charge.

Another object of the invention is to provide a selfpropelled projectile provided with the aforementioned improved ejectable obturating and igniting device.

Further features and advantages of the invention will become apparent from the ensuing description, with reference to the accompanying drawings to which the invention is in no way limited.

FIG. 1 is a view partly in longitudinal section and partly in elevation of a projectile provided with an improved ejectable obturating and igniting device;

FIG. 2 is a longitudinal sectional view of said device before ignition;

FIG. 3 is a partial longitudinal sectional view of said device, the piston being shown in its position after ignition and before ejection of the device from the nozzle of the projectile, and

FIG. 4 is a partial view similar to FIG. 3 of a modification of the device according to the invention.

With reference to FIG. 1, the invention is shown ap plied to a self-propelled projectile A which comprises a body a having a cylindro-ogival shape and provided at the forward end with a conventional fuse-sleeve-relay b adapted to ignite the explosive or other charge 0 on impact. The explosive charge c has an annular cross-sectional shape since it has an axial cavity d in which is disposed a tubular self-propelling charge e. The two charges 0 and e are separated by a thin composite wall 1 formed, for example, from an inner fortion of extra mild steel and an outer heat insulating layer. Forward of the propelling charge e there is disposed a charge of black powder g adapted to be pro-ignited so that it in turn ignites said propelling charge e.

At the rear, the body a of the projectile comprises an attached base It constituting the divergent portion i of a gas ejection nozzle. The body of said nozzle is preferably constituted by an inserted member 1'.

It is in the divergent portion 1 of the nozzle that there is disposed for the purpose of igniting the powder g and consequently the propelling charge e, an ejectable 0bturating and igniting device B according to the invention, this device being adapted to function, as concerns ignition, under the effect of the gases of an auxiliary launching charge in a tail unit C comprising a launching powder cartridge k disposed in a tube 1 carried by a support m which is adapted to rest in the launching tube D, and a number of additional charges placed on the tube l. The support is provided with apertures 0 and p, the latter communicating with a cavity q into which the ejectable device B extends rearwardly.

With reference to FIGS. 2 and 3 which show the device B on an enlarged scale, the device B comprises a metal body l which is adapted to bear against the divergent portion i of the nozzle through the medium of a flange 2. Fluidtightness is achieved by a sealing ring 3 whereas the device B is maintained in position by a ring 4 which is composed of tin or like material which is easily sheared and is inserted in a groove in the part it of the nozzle.

The body 1 has on its longitudinal axis X-X a stepped bore composed of a smooth portion 5, a screwthreaded portion 6 and cylindrical smooth portions 7, 8, 9 and 10 arranged as shown.

Screwed in the screwthreaded portion 6 is a pyrotechnic relay 11 containing a charge of black ignition powder 12 fluidtightness for this relay being provided by a sealing element 13.

Maintained in the cylindrical cavity or portion 7 by the screwthereaded engagement of the relay ii, is an assembly comprising in the following order starting from the forward end: a gasket 14, the metal body of a first part of a pyrotechnic time delay, a second gasket 16, the plastic body 17 of a second part of said pyrotechnic time delay, a sealing ring 18, a metal spacer ring 19 and a primer carrier 20. r

The forward gasket 14 has its central aperture filled with black powder 21 adapted to be ignited by a rather long train of fusible time delay powder disposed in the body 15 in the form of two coils, disposed at 22 and 23 in unclosed grooves formed in the forward and rear faces of the body 15, and portions by way of which said coils communicate with one another and which are disposed in oblique apertures 24 formed in said body.

The forward part of the time delay constructed in this manner is completed by a rear part formed by a portion of fusible powder 26 compressed in an axial aperture 27 in the body 17 of plastic material, that is, a material having a coefficient of expansion substantially equal to that of the portion of powder 26. In this way, temperature variations do not cause the portion 26 to come away from the wall of its housing, which would create a danger of the igniting gases short-circuiting this portion of powder.

The igniting gases are produced by a primer 28 located in the primer carrier which is provided with forward orifices 29 for the passage of the gases produced by the primer, and lateral apertures 29a the function of which will be explained hereinafter.

The rear face of the primer 28 is protected by a thin sheet 30 of copper or like material. It is adapted to be stuck, afer perforation of the thin sheet 39, by a firing pin 31 fixed to the centre of the forward face of a piston 32 slidably mounted in the part 8 of the axial aperture in the body 1 which constitutes a cylinder. Strict fiuidtightness is achieved around the piston by a sealing ring 33.

The piston 32 extends rearwardly in the form of a piston rod 34 which is slidably mounted in a guide ring 35 maintained clamped and centered in the counterbore 10 by a rear member 36 screwthreadedly engaged at 37 on the end of the body I.

Said member 36 has an axial bore 38 which communicates with the exterior by way of radial apertures 39 and the body 1 also comprises radial apertures 40 by way of which the cavity 9 behind the piston 32 around the rod 34 communicates with the exterior.

The device operates in the following manner:

Before firing or launching the projectile, the component parts are in the positions shown in FIG. 2. The firing pin 31 is at a very short distanceabout a small fraction of millimeterfrom the thin sheet 30, this distance is such that, even if the projectile assumes in the course of handling a position in which its ogive is directed downwardly, the forward displacement of the piston 32 under the effect of gravity does not gain sufficient impetus to permit the firing pin 31 to perforate the thin sheet 30 and strike the primer 28. The projectile is therefore safe to store and handle.

The firing pin-carrying piston is held in this position by a retaining device. It cannot move rearwardly since the piston rod 34 bears against a locking member or crossmember 41 which forms part of said retaining device and is pressed out from celluloid or other combustible material and is disposed in the bore 38 of the member 36 in which it constitutes a spacer member.

When firing or launching by effecting a percussion at n.

(FIG. 1), the auxiliary launching charge k and the additional charges are ignited, and the ignited gases emanating from these charges enter the chamber q surrounding the device B by Way of the apertures p on the support In. In this chamber these gases under pressure enter the cavity 9 behind the firing pin 31 through the apertures 40 in the body 1 and cause the piston 32 to move forwardly with sufiicient force to enable the firing pin 31 to perforate the thin sheet 30 and strike the primer 28.

But these gases under very high pressure emanating from the launching charge cannot in any way pass into the chamber 7 containing the time delay charges located in the bodies 17 and 15 and more particularly cannot short-circuit the portion 26 since they are completely arrested by the sealing ring 33 encompassing the piston 32, which ring is preferably of the self-tightening type.

But at the same time as the piston 32 and the firing pin 31 are projected forwardly, the gases emanating from the launching charge enter by way of the apertures 39 the rear part of the device B and ignite the cross-member 41 which is very rapidly destroyed and no longer prevents the piston 32 from moving to its extreme rear position.

Consequently, as soon as the projectile leaves the launching or firing tube D, the counterbore 9 and the rear chamber 38 are put in communication with the atmos phere by way of the apertures 40 and 39 respectively and the cavity 4-2 formed in front of the primer 28 is full of ignited gases which come from this primer and reach this cavity by way of the orifices 29 of the primer carrier.

The moderate pressure of these gases is exerted through the apertures 29a on the forward face of the piston 32 and as the rear face of the latter is maintained at the atmospheric pressure this piston moves rearwardly under the action of these gases and assumes the rear position shown in FIG. 3 in which it is located in the counterbore 9 which it can enter without difiiculty, since the circumferential clearance provided between the wall of this bore and the piston 32 avoids the creation of any back pressure on the rear face of the piston.

Owing to the withdrawal of the piston to the position shown in FIG. 3, it is clear that the chamber 42 is put in communication with the atmosphere by the apertures 29a of the primer carrier 26. Consequently, the gases coming from the primer 28 are practically at atmosperic pressure and although they are such as to insure the ignition of the rectilinear time delay portion 26 they are incapable of passing between this portion 26 and the wall of the aperture 27 which contains the portion 26 even if this portion ceases to remain in contact with this wall, which is normally impossible.

There is therefore a regular progression of the combustion of the portion 26 which in turn ignites the powder charge in the form of a long train contained in the forward part 15 of the time delay and this long train finally ignites, through the medium of the powder 21 contained in the gasket 14, the powder 12 the flames of which in turn travel along the axial aperture r (FIG. 1) in the propelling charge 2 and ignite the latter through the medium of the black powder g.

FIG. 4 shows a modification of the invention in which the retaining device for the piston 32 is modified in that the cross-member 41 of the first embodiment is replaced by a ball or locking member 43 engaged in a recess 44 in the rod 34 of the piston 32, this ball bearing against the part-conical face 45 of the guide member 35 so as to temporarily maintain the piston in its forward position of rest.

When firing 0r launching, the gases under pressure from the auxiliary launching charge cause, as in the first embodiment, the forward displacement of the piston 32 and the balls 43 which were wedged against the guide member 35 are released and escape into the counterbore 9 so that, as soon as the projectile has left the launching tube and the pressure has dropped in this counterbore, the piston 32 can freely withdraw up to its contact with the guide member 35 and put the chamber 42 in communication with the atmosphere by way of the apertures 29a in the primer carrier 20, the bore 8 and the apertures 40.

Although specific embodiments of the invention have been described, many modifications and changes may be made therein without departing from the scope of the invention as defined in the appended claims.

Having now described my invention'what I claim as new and desire to secure by Letters Patent is:

1. An igniting device for a self-propelled projectile adapted to be shot out of a launching tube by the gases of an auxiliary launching charge, said device comprising the combination of means defining a body, a chamber having an axis and formed in the body, a primer device located adjacent one end of the chamber, a piston having a forward face in facing relation to the primer device and a rear face and slidable in a gas-tight manner along said axis in the chamber between a rear position and a forward position, a firing pin carried by the forward face of the piston and capable of striking and penetrating the primer device when the piston slides to said forward position, the primer device being adapted to ignite upon application thereon of a given percussion force by the firing pin, means defining a retaining device mounted in the body for preventing the piston from sliding rearwardly from said forward position beyond an intermediate position in which the firing pin is at such distance, from the primer device that the piston, when moved relative to the primer device by the force of gravity along said axis when said axis is vertical, can not gain sulficient impetus to permit the firing pin to apply said given percussion force on the primer device, said retaining device including a locking member ordi narily lockingly engaged with the piston, and means responsive to the action of the gas of the auxiliary launching charge and associated with the locking member for removing the locking member from engagement with the piston and thus rendering the piston free to slide rearwardly when the auxiliary launching charge is ignited, and a passageway formed in the body and putting the chamber in communication with the exterior of the body, the passageway opening into .the chamber in such position that the passageway is located on the side of the piston corresponding to said rear face of the piston in said intermediate position thereof and is located on the side of the piston-corresponding to said forward face of the piston in said rear position thereof, whereby on launchingthe projectile said gases of the auxiliary launching charge drive the piston at a force exceeding said percussion force to said forward position and gases emanating from the ignited primer device drive the piston to said rear position and escape through the passageway.

2. An igniting device as claimed in claim 1, wherein the primer device comprises a housing fixed to the body, a primer powder charge filling the housing, a thin soft metal sheet mounted on the housing and, adjoining the primer powder charge, the sheet being interposed between the primer powder charge and the firing pin and adapted to be pierced by the firing pin upon application of a given percussion force by the firing pin so that the primer powder charge is ignited by the firing pin, the firing pin being at a distance of a fraction of a millimetre from the metal sheet when the piston is in said intermediate position.

3. An igniting device for a self-propelled projectile adapted to be shot out of a launching tube by the gases of an auxiliary launching charge, said device comprising the combination of means defining a body, a gas-tight chamber formed in the body, the chamber having an axis and a forward end wall and a rear end wall, a transverse partition wall in axially spaced relation to said forward end Wall and dividing the chamber into a forward compartment and a rear compartment, a time-delay powder charge provided in said forward end wall, a primer device provided in said rear compartment and supported by said partition wall, the primer device including a primer powder charge, small orifices formed in the partition wall putting the primer powder charge in communication with the forward compartment, throughway apertures in the partition wall putting the forward cornpartment in communication with the rear compartment, a piston slidable in a gas-tight manner along said axis in the rear compartment between a rear position and a forward position, a firing pin carried by the piston and capable of striking the primer device when the piston slides to said forward position, the primer device being adapted to be ignited upon application of a given percussion force by the firing pin, means defining a retaining device provided in the body for preventing the piston from sliding rearwardly from the forward position beyond an intermediate position in which the firing pin is at such distance from the primer device that the piston, when moved relative to the primer device by the force of gravity along said axis when said axis is vertical, does not gain sufficient impetus to permit the firing pin to apply said given percussion force on the primer device, said retaining device including a locking member ordinarily lockingly engaged with the piston, and means responsive to the action of the gas of the auxiliary launching charge and associated with the locking member for removing the locking member from engagement with the piston and thus rendering the piston free to slide rearwardly when the auxiliary launching charge is ignited, and a passageway formed in the body and putting said rear compartment of the chamber in communication with the ext rior of the body, the passageway opening into the chamber in such position as to be located between the piston and said rear end wall in the intermediate position of the piston and located between the partition wall and the piston in said rear position of the piston, whereby said gases of the auxiliary launching charge drive the piston to said forward position and gases emanating from the primer powder charge drive the piston to said rear position and escape by way of said passageway.

4. An igniting device for a self-propelled projectile adapted to be shot out of a launching tube by the gases of an auxiliary launching charge, said device comprising means defining a body, a chamber having an axis and formed in the body, a primer device located adjacent one end of the chamber, a piston having a forward face in facing relation to the primer device and a rear face and slidable in a gas-tight manner along said axis in the chamber between a rear position and a forward position, a firing pin carried by the forward face of the piston and capable of striking and penetrating the primer device when the piston slides to said forward position, the primer device being adapted to ignite upon application thereon of a given percussion force by the firing pin, a retaining device for preventing the piston from sliding rearwardly from said forward position beyond an intermediate position in which the firing pin is at such distance from the primer device that the piston, when moved toward the primer device by the force of gravity along said axis when said axis is vertical, can not gain sufiicient impetus to perunit the firing pin to apply said given percussion force on the primer device, the retaining device comprising an abutment face provided on the body and disposed at the end of the chamber remote from the primer device, a combustible spacer member interposed between and in contact with the piston and the abutment face, and an aperture formed in the body and putting the spacer member in communication with the exterior of the body whereby on launching the projectile said gases destroy the spacer member, and a passageway formed in the body and putting the chamber in communication with the exterior of the body, the passageway opening into the chamber in such position that the passageway is located at the rear of the piston in said intermediate position of the piston and forward of said forward face of the piston in said rear position of the piston, whereby on launching the projectile said gases of the auxiliary launching charge drive the piston at a force exceeding said percussion force to said forward position and gases emanating from the ignited primer device drive the piston to said rear position and escape through the passageway.

5. An igniting device for a self-propelled projectile adapted to be shot out of a launching tube by the gases of an auxiliary launching charge, said device comprising means defining a body, a chamber having an axis and formed in the body, a primer device located adjacent one end of the chamber, a piston having a forward face in facing relation to the primer device and a rear face and slidable in a gas-tight manner along said axis in the chamber between a rear position and a forward position, a firing pin carried by the forward face of the piston and capable of striking and penetrating the primer device when the piston slides to said forward position, the primer device being adapted to ignite upon application thereon of a given percussion force by the firing pin, a retaining device for preventing the piston from sliding rearwardly from said forward position beyond an intermediate position in which the firing pin is at such distance from the primer device that the piston, when moved toward the primer device by the force of gravity along said axis when said axis is vertical, can not gain sufiicient impetus to permit the firing pin to apply said given percussion force on the primer device, the retaining device comprising an axially etxending piston rod fixed to the piston and slidably mounted in the body, a recess formed in the body, a recess formed in the piston rod, the recesses having abutment faces in axially facing relation to each other and a locking member trapped within the recesses in said intermediate position of the piston and engaged between the abutment faces so as to prevent movement of the piston toward said rear position, the abutment faces moving away from each other and allowing the locking member to escape into the chamber when the piston slides to said forward position, and a passageway formed in the body and putting the chamber in communication with the exterior of the body, the passageway opening into the chamber in such position that the pasageway is at the rear of the rear face of the piston in said intermediate position of the piston and forward of said forward face of the piston in said rear position of the piston, whereby on launching the projectile said gases of the auxiliary launching charge drive the piston at a force exceeding said percussion force to said forward position and gases emanating from the ignited primer device drive the piston to said rear position and escape through the passageway.

6. An igniting device for a self-propelled projectile adapted to be launched from a launching tube by the gases of an auxiliary launching charge said device com-.

8 prising means defining a body, a chamber formed in the body and having a longitudinal axis and a forward end portion, a time-delay powder charge provided in the forward end portion of the chamber, a primer device mounted in the chamber adjacent the time-delay powder charge, a

piston having a forward face in facing relation to the primer device and a rear face and slidable in a gas-tight manner in the chamber along said axis between a rear position and a forward position, the primer device comprising a housing extending partially across the chamber and fixed to the body and containing a primer powder charge, a soft metal sheet in fixed relation to the housing and adjoining the primer powder charge, an orifice in the housing putting the primer powder charge .in communication with the time-delay powder charge, a pointed firing pin being provided on said forward face of the piston and adapted to perforate the soft metal sheet and ignite the primer powder charge when said gases drive the piston to said forward position, a retaining device for preventing the piston from sliding rearwardly from said forward position beyond an intermediate position in which the firing pin is spaced axially from the metal sheet a fraction of a millimetre, the retaining device comprising an abutment face provided on the body and disposed at the end of the chamber remote from the primer device, a combustible spacer member interposed between the piston and the abutment face, and an aperture formed in the body and putting the spacer member in communication with the exterior of the body whereby on launching the projectile said gases destroy the spacer member, and a passageway formed in the body and putting the chamber in communication with the exterior of the body, the passageway opening into the chamber in such position that the passageway is located at the rear of said rear face of the piston in said intermediate position thereof and forward of said forward face of the piston in said rear position thereof.

References Cited in the file of this patent UNITED STATES PATENTS 547,850 Hathaway Oct. 15, 1895 1,491,000 Brandt et a1 Apr. 22, 1924 2,462,305 Catlin Feb. 22, 1949 2,737,892 Dalton et al Mar. 13, 1956 2,773,448 Jasse Dec. 11, 1956 2,944,486 Jasse July 12, 1960

Claims (1)

1. AN IGNITING DEVICE FOR A SELF-PROPELLED PROJECTILE ADAPTED TO BE SHOT OUT OF A LAUNCHING TUBE BY THE GASES OF AN AUXILIARY LAUNCHING CHARGE, SAID DEVICE COMPRISING THE COMBINATION OF MEANS DEFINING A BODY, A CHAMBER HAVING AN AXIS AND FORMED IN THE BODY, A PRIMER DEVICE LOCATED ADJACENT ONE END OF THE CHAMBER, A PISTON HAVING A FORWARD FACE IN FACING RELATION TO THE PRIMER DEVICE AND A REAR FACE AND SLIDABLE IN A GAS-TIGHT MANNER ALONG SAID AXIS IN THE CHAMBER BETWEEN A REAR POSITION AND A FORWARD POSITION, A FIRING PIN CARRIED BY THE FORWARD FACE OF THE PISTON AND CAPABLE OF STRIKING AND PENETRATING THE PRIMER DEVICE WHEN THE PISTON SLIDES TO SAID FORWARD POSITION, THE PRIMER DEVICE BEING ADAPTED TO IGNITE UPON APPLICATION THEREON OF A GIVEN PERCUSSION FORCE BY THE FIRING PIN, MEANS DEFINING A RETAINING DEVICE MOUNTED IN THE BODY FOR PREVENTING THE PISTON FROM SLIDING REARWARDLY FROM SAID FORWARD POSITION BEYOND AN INTERMEDIATE POSITION IN WHICH THE FIRING PIN IS AT SUCH DISTANCE, FROM THE PRIMER DEVICE THAT THE PISTON, WHEN MOVED RELATIVE TO THE PRIMER DEVICE BY THE FORCE OF GRAVITY ALONG SAID AXIS WHEN SAID AXIS IS VERTICAL, CAN NOT GAIN SUFFICIENT IMPETUS TO PERMIT THE FIRING PIN TO APPLY SAID GIVEN PERCUSSION FORCE ON THE PRIMER DEVICE, SAID RETAINING DEVICE INCLUDING A LOCKING MEMBER ORDINARILY LOCKINGLY ENGAGED WITH THE PISTON, AND MEANS RESPONSIVE TO THE ACTION OF THE GAS OF THE AUXILIARY LAUNCHING CHARGE AND ASSOCIATED WITH THE LOCKING MEMBER FOR REMOVING THE LOCKING MEMBER FROM ENGAGEMENT WITH THE PISTON AND THUS RENDERING THE PISTON FREE TO SLIDE REARWARDLY WHEN THE AUXILIARY LAUNCHING CHARGE IS IGNITED, AND A PASSAGEWAY FORMED IN THE BODY AND PUTTING THE CHAMBER IN COMMUNICATION WITH THE EXTERIOR OF THE BODY, THE PASSAGEWAY OPENING INTO THE CHAMBER IN SUCH POSITION THAT THE PASSAGEWAY IS LOCATED ON THE SIDE OF THE PISTON CORRESPONDING TO SAID REAR FACE OF THE PISTON IN SAID INTERMEDIATE POSITION THEREOF AND IS LOCATED ON THE SIDE OF THE PISTON CORRESPONDING TO SAID FORWARD FACE OF THE PISTON IN SAID REAR POSITION THEREOF, WHEREBY ON LAUNCHING THE PROJECTILE SAID GASES OF THE AUXILIARY LAUNCHING CHARGE DRIVE THE PISTON AT A FORCE EXCEEDING SAID PERCUSSION FORCE TO SAID FORWARD POSITION AND GASES EMANATING FROM THE IGNITED PRIMER DEVICE DRIVE THE PISTON TO SAID REAR POSITION AND ESCAPE THROUGH THE PASSAGEWAY.

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