Description:FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10 And Rule 13)

Title of the invention:
AN OPENING AND CLOSING MECHANISM FOR A BARREL CLOSURE UNIT
Applicant:
BHARAT FORGE LIMITED
An Indian Entity having address as:
Mundhwa, Pune - 411036,
Maharashtra, India.

The following specification particularly describes the invention and the manner in which it is to be performed.
CROSS-REFERENCE TO RELATED APPLICATIONS AND PRIORITY
[0001] The present application claims no priority from any of the patent application(s).
FIELD OF INVENTION
[0002] The present invention relates to the field of an opening and closing mechanism for a barrel closure unit. More particularly, the present invention relates to an actuator system used for operating the barrel closure unit.
BACKGROUND OF THE INVENTION
[0003] This section is intended to introduce the reader to various aspects of art, which may be related to various aspects of the present disclosure that are described or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements in this background section are to be read in this light, and not as admissions of prior art. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also correspond to implementations of the claimed technology.
[0004] A concept of using a closure mechanism for a barrel of a projectile launching system is well known in the art. The closure mechanism is considered as a key part in the field of projectile launching system. Currently various types of closure mechanisms are used for barrel unit such as ‘sliding wedge block mechanism’ and ‘screw type mechanism’. The type of closure mechanism used in projectile launching system is facilitated by the range and the operating conditions.
[0005] The conventional closing and opening mechanism for the barrel closure unit was operated manually during word war era. Nowadays, the operation is upgraded by using rack and pinion mechanism or geartrain powered by hydraulic or pneumatic cylinders. In existing art, the hydraulic or pneumatic actuators and their associated geartrains are placed with the barrel structure. Such a placement leads to cause repetitive damages during the recoil movement of the barrel due to shocks.
[0006] The conventional opening and closing mechanism are complex in construction. Such mechanism needs exhaustive maintenance regularly to achieve efficient working. The complex construction of the mechanism can lead to cause delay in maintenance and repair during emergency situations. Further, the failure in closing of the barrel closure unit can cause accidents which leading to injuries or fatal.
[0007] In light of the above stated discussion, there exists a need of an improved system for opening and closing of the barrel unit to overcome the above stated disadvantages.
SUMMARY OF THE INVENTION
[0008] Before the present system (or apparatus) and method, and its components are described, it is to be understood that this disclosure is not limited to the system and its arrangement as described, as there can be multiple possible embodiments which are not expressly illustrated in the present disclosure. It is also to be understood that the terminology used in the description is for the purpose of describing the versions or embodiments only and is not intended to limit the scope of the present application. This summary is not intended to identify essential features of the claimed subject matter nor is it intended for use in detecting or limiting the scope of the claimed subject matter.
[0009] In one non-limiting embodiment, an opening and closing mechanism for a barrel closure unit is disclosed. Further, the opening and closing mechanism includes an actuator configured to transmit power to a gear mechanism. Further, the gear mechanism comprises a rack rod which is connected to at least one end of the actuator, and a pinion which is configured to mesh with the moving rack rod. Further, a crank shaft is configured to couple the barrel closure unit to the pinion mechanism. Furthermore, the crank shaft is provided with an extended end which is configured to engage with a precise slot of the pinion. Additionally, the extended end of the crank shaft is configured to provide engaging movement and disengaging movement in relation to the precise slot of the pinion.
[0010] In an embodiment, the disengaging movement of the extended end may be facilitated by recoil movement of a barrel and, the engaging movement of the extended end may be facilitated by retaining movement of the barrel.
[0011] In another embodiment, the said actuator may be at least a hydraulic, or a pneumatic, or an electric actuator or a combination thereof. Further, the said rack rod may be connected to the at least one end of the actuator to perform linear displacement.
[0012] In yet another embodiment, the shape of the extended end may be one of square, rectangular, trapezoidal, and triangular shape.
[0013] In yet another embodiment, the said pinion may be a sector gear provided with the precise slot. Further, the pinion may be converts linear displacement of the rack rod into rotary displacement.
[0014] In yet another embodiment, the pinion may be provided with plurality of bearings and suspended at the pinion housing.
[0015] In yet another embodiment, the said rack rod may be enclosed within rack bracket and may be configured to extend into an extended housing during forward displacement.
[0016] In yet another embodiment, the said rack rod, the pinion, and the actuator may be mounted over a main structure.
[0017] In yet another embodiment, the said barrel closure unit may be configured to open during forward linear displacement of actuator and, close during rearward linear displacement of the actuator.
[0018] In yet another embodiment, the position of the crank shaft and the pinion may remain locked independently during recoil movement and retaining movement of the barrel (126). Further, a locking mechanism in the rack rod (114) may lock the position of the pinion (112). Furthermore, a closure locking arrangement of the barrel closure unit (124) locks the position of the crank shaft (122).
[0019] In another non-limiting embodiment, a method of operation of a barrel closure unit is disclosed. The method includes a forward displacement of an actuator which is configured to obtain an opening condition of the barrel closure unit. Further, a rearward displacement of the actuator which is configured to obtain a closing condition of the barrel closure unit. Furthermore, the method also includes a disengaging movement of an extended end from a precise slot of a pinion during recoil movement of a barrel. Further, an engaging movement of an extended end within a precise slot of a pinion during retaining movement of the barrel.
BRIEF DESCRIPTION OF DRAWINGS
[0020] Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
[0021] Figure 1 illustrates an opening and closing mechanism (100), in accordance with various embodiment of the present subject matter.
[0022] Figure 2 illustrates an exploded view (100a) of an opening and closing mechanism (100), in accordance with various embodiment of the present subject matter.
[0023] Figure 3 illustrates a detailed view (100c) of a crank shaft (122) with an extended end (120) engaged within a precise slot (118) of a pinion (112), in accordance with various embodiment of the present subject matter.
[0024] Figure 4 illustrates an opening condition (200) of the barrel closure unit
(124), in accordance with various embodiment of the present subject matter.
[0025] Figure 5 illustrates a closing condition (200a) of the barrel closure unit
(124), in accordance with various embodiment of the present subject matter.
[0026] Figure 6 illustrates a disengaging movement (300) during a recoil movement of a barrel (126), in accordance with various embodiment of the present subject matter.
[0027] Figure 7 illustrates an engaging movement (300a) during a retaining movement of a barrel (126), in accordance with various embodiment of the present subject matter.
[0028] It should be noted that the accompanying figures are intended to present illustrations of exemplary embodiments of the present disclosure. These figures are not intended to limit the scope of the present disclosure.
DETAILED DESCRIPTION
[0029] Reference throughout the specification to “various embodiments,” “some embodiments,” “one embodiment,” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in various embodiments,” “in some embodiments,” “in one embodiment,” or “in an embodiment” in places throughout the specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.
[0030] The words "comprising," "having," "containing," and "including," and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items or meant to be limited to only the listed item or items. It must also be noted that, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. For example, the term “an article” may include a plurality of articles unless the context clearly dictates otherwise. Although any methods similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present disclosure, the exemplary methods are described. The disclosed embodiments are merely exemplary of the disclosure, which may be embodied in various forms.
[0031] Various modifications to the embodiment may be readily apparent to those skilled in the art and the generic principles herein may be applied to other embodiments. However, one of ordinary skill in the art may readily recognize that the present disclosure is not intended to be limited to the embodiments illustrated but is to be accorded the widest scope consistent with the principles and features described herein. The detailed description of the invention will be described hereinafter referring to accompanied drawings.
[0032] As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. Further, the terms and phrases used herein are not intended to be limiting but rather to provide an understandable description of the invention.
[0033] Those with ordinary skill in the art will appreciate that the elements in the figures are illustrated for simplicity and clarity and are not necessarily drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated, relative to other elements, in order to improve the understanding of the present invention. There may be additional components described in the foregoing application that are not depicted on one of the described drawings. In the event such a component is described, but not depicted in a drawing, the absence of such a drawing should not be considered as an omission of such design from the specification.
[0034] In the accompanying drawings components have been represented, showing only specific details that are pertinent for an understanding of the present invention so as not to obscure the disclosure with details that will be readily apparent to those with ordinary skill in the art having the benefit of the description herein.
[0035] In accordance with an embodiment of the present subject matter, referring to figure 1, figure 2, and figure 3, an opening and closing mechanism (100) with an exploded view (100a), a detailed view (100c) of an extended end (120) with a precise slot (118) is described herein. Further, referring to figure 6, and figure 7, an engaging movement (300a) and disengaging movement (300) in relation to the precise slot (118) is also described herein.
[0036] In a non-limiting embodiment, an opening and closing mechanism (100) for a barrel closure unit (124) is disclosed. Further, the opening and closing mechanism (100) includes an actuator (102) which is configured to transmit power to a gear mechanism. Further, the gear mechanism includes a rack rod (114) mechanism which is configured to connect at least one end of the actuator (102) and a pinion (112) which is configured to mesh with the moving rack rod (114). Further, a crank shaft (122) is configured to couple the barrel closure unit (124) to the pinion (112). In addition, the crank shaft (122) is provided with an extended end (120) configured to engage with a precise slot (118) of the pinion (112). Furthermore, the extended end (120) of the crank shaft (122) is configured to provide engaging movement (300a) and disengaging movement (300) in relation to the precise slot (118) of the pinion (112).
[0037] In another embodiment, the barrel (126) may be a part of a projectile launching system (not shown). Further, the barrel (126) may provide a passage to the projectile to launch or eject. Further, the barrel (126) may be manufactured in variety of diameters and length. Furthermore, the barrel (126) may be made by process of forging, or turning, or moulding or any other. In addition, the opening and closing mechanism (100) may be arranged along with the length of the barrel (126). Further, the barrel (126) may be arranged to accommodate the reciprocating motion. Further, the barrel (126) may be provided with a suspension or a shock absorption system to withstand with shocks.
[0038] In one another embodiment, the barrel closure unit (124) may be a screw type closure unit or a sliding type closure unit. Further, the barrel closure unit (124) may be mounted on the rearmost end of the barrel (126). Further, the crank shaft (122) may be provided to couple the barrel closure unit (124) to the pinion (112). Further, the barrel closure unit (124) may be provided with a locking mechanism. Further, the barrel closure unit (124) may remain close during the projectile launching phase. Furthermore, the barrel closure unit (124) may remain open after completion of projectile launching phase. In other words, the barrel closure unit (124) may remain open during loading of the projectile in the barrel (126).
[0039] In yet another embodiment, the opening and closing mechanism (100) may include an actuator (102). Further, the actuator (102) may be one of a hydraulic, or a pneumatic, or an electric actuator. The actuator (102) may be mounted along with length of the barrel (126). Further, the actuator (102) may be configured to provide linear displacement to the gear mechanism. Further, the actuator (102) may include an inlet and an outlet port for pneumatic and/or hydraulic fluid flow in case of pneumatic and/or hydraulic actuator. Furthermore, associated components such as reservoirs, tubes, valves, pumps, compressors may be provided along with the actuator circuit. In the case of the electric actuator, the electric motor and powering supply may be provided.
[0040] In yet another embodiment, the opening and closing mechanism (100) may include a gear mechanism. The gear mechanism may comprise the rack rod (114) and the pinion (112). Further, the rack rod (114) may be attached to the end of the actuator (102). Further, the rack rod (114) may move linearly with respect to the linear of the actuator (102). Furthermore, the pinion (112) may be in meshing contact with the rack rod (114). Further, the forward movement of the rack rod (114) may rotate the pinion (112) in clockwise rotation. Further, the rearward movement of the rack rod (114) may rotate the pinion (112) in anti-clockwise direction.
[0041] Additionally, the pinion (112) may be provided to convert linear motion of the rack rod (114) into rotary motion. Further, the pinion (112) may be provided with the precise slot (118). The precise slot (118) may be configured to accommodate the extended end (120) of the crank shaft (122). Further, the shape of the precise slot (118) may be dependent upon the shape of the extended end (120). The shape of the precise slot (118) may be one of a square, or a rectangular, or a triangular, or a trapezoidal shape. In an embodiment of the present invention, the shape of the extended end (120) and/or precise slot (118) may be any quadrilateral shape. Further, the pinion (112) may be a sector gear. Further, the pinion (112) may be provided to rotate clockwise and anti-clockwise in limited rotary angle. Furthermore, the axis of the pinion (112) may be perpendicular to the axis of the rack rod (114).
[0042] In yet another embodiment, the crank shaft (122) may be provided to couple the pinion (112) of the opening and closing mechanism (100) to the barrel closure unit (124). Further, the axis of the crank shaft (122) may be inline with the axis of the pinion (112). Further, the crank shaft (122) may include the extended end (120). Further, the extended end (120) may be configured to engage within the precise slot (118) of the pinion (112) during launching of the projectile through the barrel (126). In addition, the extended end (120) may be configured to provide disengaging movement through the precise slot (118) during recoil movement of the barrel (126). Further, during the engaged condition of the extended end (120) of the crank shaft (122), the barrel closure unit (124) may be opened or closed by using the opening and closing mechanism (100).
[0043] In yet another embodiment, the components of the opening and closing mechanism (100) may be enclosed within one or more housings. Further, the rack rod (114) may be enclosed within a rack bracket (104). Further, the extended position of the rack rod (114) during the forward displacement of the actuator (102) may be accommodated within an extended housing (108). Furthermore, the pinion (112) of the gear mechanism may be enclosed within the pinion housing (106). Further, the housing arrangements (106, 108, 104) may be provided to the gear mechanism to protect the components from external factors. In another aspect, the housing arrangements (106, 108, 104) may be configured to provide lubrication space.
[0044] Additionally, the pinion housing (106) configured to enclose the pinion (112) may include mounting arrangements. Further the said mounting arrangements may be provided to hold the pinion (112) at one end. Further, the mounting arrangement may include plurality of bearings (116) to provide rotational movement to the pinion (112) mounted on the pinion housing (106). The plurality of bearings (106) may include but not limited to all types a ball bearing, or a roller bearing.
[0045] In yet another embodiment, a main structure (110) may be provided to accommodate the components of the opening and closing mechanism (100). More specifically, the actuator (102), the rack rod (114), and the pinion (112) may be mounted on the main structure (110). Further, the main structure (110) maybe mounted along with the axis of the barrel (126). Further, the main structure (110) may be independent from the barrel (126). Furthermore, the main structure (110) may carry the pinion housing (106), extended housing (108), and rack bracket (104). Furthermore, the main structure (110) may be welded or mechanically fixed to the components of the opening and closing mechanism (100).
[0046] In another aspect, the main structure (110) may be a fixed structure. In an example, the main structure (110) may be fixedly mounted to the base body of the projectile launching system. In another example, the main structure (110) may be fixedly attached to any component of the projectile launching system.
[0047] Now referring to figure 4, 5 6, and 7, a method of operation of a barrel closure unit (124) is disclosed. The method includes a first step of forward displacement of the actuator (102) configured to obtain an opening condition (200) of the barrel closure unit (124). Further, a step including a rearward displacement of the actuator (102) configured to obtain a closing condition (200a) of the barrel closure unit (124). Additionally, after launch of the projectile, the next step includes a disengaging movement (300) of an extended end (120) from a precise slot (118) of a pinion (112) during recoil movement of a barrel (126). Again, an engaging movement (300a) of an extended end (120) within a precise slot (118) of a pinion (112) during end stroke of retaining movement of the barrel (126).
[0048] In yet another embodiment, the barrel closure unit (124) may be in the opening condition (200) during forward linear displacement of actuator (102). Further, the barrel closure unit (124) may be in the closing condition (200a) during rearward linear displacement of the actuator (102). More specifically, the forward movement of the actuator (102) may facilitate clockwise rotation of the pinion (112) which may lead to clockwise rotation of the engaged crank shaft (122) causing the opening condition (200). Further, the rearward movement of the actuator (102) may facilitate anti-clockwise rotation of the pinion (112) which may lead to anti-clockwise rotation of the engaged crank shaft (122) causing the closing condition (200a).
[0049] In yet another embodiment, the disengaging movement (300) of the extended end (120) of the crank shaft (122) from the precise slot (118) of the pinion (112) during recoil movement of a barrel (126) may disengage the barrel closure unit (124) coupled with the opening and closing mechanism (100). Further, the engaging movement (300a) of the extended end (120) of the crank shaft (122) with the precise slot (118) of the pinion (112) during retaining movement of a barrel (126) may again engage the barrel closure unit (124) with the opening and closing mechanism (100). Furthermore, after the engagement motion (300a), the barrel closure unit (124) may be again actuated by opening and closing mechanism (100) to obtain the opening condition (200). Further, after the opening condition (200), the barrel closure unit (124) may be again actuated by opening and closing mechanism (100) to obtain the closing condition (200a).
[0050] In yet another embodiment, the position of the crank shaft (122) may be locked during recoil and retaining movement of the barrel (126). Further, the position of the pinion (112) may remain locked during recoil and retaining movement of the barrel (126). Additionally, a locking mechanism may be provided in the rack rod (114) to lock the position of the pinion (112). Further, a closure locking arrangement may be provided in the barrel closure unit (124) to lock the position of the crank shaft (122). In other instance, the locking condition of the crank shaft (122) and pinion (112) may be provided to achieve precise engaging movement (300a) during retaining movement of the barrel (126).
[0051] In an exemplary embodiment, the orientation of the opening and closing mechanism (100) may be changed. The opening and closing mechanism (100) may be mounted with opposite orientation than the orientation in the figures (1-7). In the view of the opposite orientation of the opening and closing mechanism (100), the forward displacement of the actuator (102) may lead to closing condition (not shown) of the barrel closure unit (124), and the rearward displacement of the actuator (102) may lead to opening condition (not shown) of the barrel closure unit (124). In the same aspect, more particularly, during forward displacement the pinion (112) may rotate anti-clockwise and may rotate the crank shaft (122) anti-clockwise leading to closing condition (not shown). Further, during rearward displacement, the pinion (112) may rotate clockwise and may rotate the crank shaft (122) clockwise leading to opening condition (not shown).
[0052] In one more exemplary embodiment, the opening and closing mechanism (100) may be used in applications not limited to a ball thrower gun, a projectile launching system, an artillery gun.
[0053] The invention is further defined by at least the examples provided in the following items:
Item 1 An opening and closing mechanism (100) for a barrel closure unit (124), comprising:
an actuator (102) configured to transmit power to a gear mechanism, wherein the gear mechanism comprises a rack rod (114) connected to at least one end of the actuator (102), and a pinion (112) configured to mesh with the moving rack rod (114); and
a crank shaft (122) configured to couple the barrel closure unit (124) to the pinion (112), wherein, the crank shaft (122) is provided with an extended end (120) configured to engage with a precise slot (118) of the pinion (112), wherein the extended end (120) of the crank shaft (122) is configured to provide engaging movement (300a) and disengaging movement (300) in relation to the precise slot (118) of the pinion (112).
Item 2 The mechanism (100) of item 1, wherein recoil movement of a barrel (126) enables disengaging movement (300) of the extended end (120), wherein retaining movement of the barrel (126) enables engaging movement (300a) of the extended end (120).
Item 3 The mechanism (100) of item 1, wherein the said actuator (102) is at least one of hydraulic actuator, pneumatic actuator, electric actuator, and combination thereof, wherein the said rack rod (114) is connected to the at least one end of the actuator (102) to perform linear displacement.
Item 4 The mechanism (100) of item 1, wherein the cross-sectional shape of the extended end (120) is at least one of square, rectangular, and triangular shape.
Item 5 The mechanism (100) of item 1, wherein the said pinion (112) is a sector gear provided with the precise slot (118), wherein the pinion (112) converts linear displacement of the rack rod (114) into rotary displacement.
Item 6 The mechanism (100) of item 1 and 6, wherein the pinion (112) is provided with plurality of bearings (116) and suspended at the pinion housing (106).
Item 7 The mechanism (100) of item 1, wherein the said rack rod (114) is enclosed within a rack bracket (104) and configured to extend into an extended housing (108) during forward displacement, wherein the said rack rod (114), the pinion (112), and the actuator (102) are mounted on a main structure (110).
Item 8 The mechanism (100) of item 1, wherein the said barrel closure unit (124) is in opening condition (200) during forward linear displacement of the actuator (102) and in closing condition (200a) during rearward linear displacement of the actuator (102).
Item 9 The mechanism (100) of item 1, wherein the position of the crank shaft (122) and the pinion (112) remains locked independently during recoil movement and retaining movement of the barrel (126), wherein a locking mechanism in the rack rod (114) locks the position of the pinion (112), wherein a closure locking arrangement of the barrel closure unit (124) locks the position of the crank shaft (122).
Item 10 A method of operation of a barrel closure unit (124), comprising steps of:
a forward displacement of an actuator (102) configured to obtain an opening condition (200) of the barrel closure unit (124);
a rearward displacement of the actuator (102) configured to obtain a closing condition (200a) of the barrel closure unit (124);
a disengaging movement (300) of an extended end (120) from a precise slot (118) of a pinion (112) during recoil movement of a barrel (126); and
an engaging movement (300a) of an extended end (120) within a precise slot (118) of a pinion (112) during end stroke of retaining movement of the barrel (126).
[0054] The foregoing description shall be interpreted as illustrative and not in any limiting sense. A person of ordinary skill in the art would understand that certain modifications could come within the scope of this disclosure.
[0055] The embodiments, examples, and alternatives of the preceding paragraphs or the description, including any of their various aspects or respective individual feature(s), may be taken independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments unless such features are incompatible.

, C , Claims:WE CLAIM:
1. An opening and closing mechanism (100) for a barrel closure unit (124), comprising:
an actuator (102) configured to transmit power to a gear mechanism, wherein the gear mechanism comprises a rack rod (114) connected to at least one end of the actuator (102), and a pinion (112) configured to mesh with the rack rod (114); and
a crank shaft (122) configured to couple the barrel closure unit (124) to the pinion (112), wherein, the crank shaft (122) is provided with an extended end (120) configured to engage with a precise slot (118) of the pinion (112), wherein the extended end (120) of the crank shaft (122) is configured to provide engaging movement (300a) and disengaging movement (300) in relation to the precise slot (118) of the pinion (112).
2. The mechanism (100) as claimed in claim 1, wherein recoil movement of a barrel (126) enables disengaging movement (300) of the extended end (120), wherein retaining movement of the barrel (126) enables engaging movement (300a) of the extended end (120).
3. The mechanism (100) as claimed in claim 1, wherein the said actuator (102) is at least one of hydraulic actuator, pneumatic actuator, electric actuator, and combination thereof, wherein the said rack rod (114) is connected to the at least one end of the actuator (102) to perform linear displacement.
4. The mechanism (100) as claimed in claim 1, wherein cross-sectional shape of the extended end (120) is at least one of square, rectangular, trapezoidal, and triangular shape.
5. The mechanism (100) as claimed in claim 1, wherein the said pinion (112) is a sector gear provided with the precise slot (118), wherein the pinion (112) converts linear displacement of the rack rod (114) into rotary displacement.
6. The mechanism (100) as claimed in claim 1 and 6, wherein the pinion (112) is provided with plurality of bearings (116) and suspended at the pinion housing (106).
7. The mechanism (100) as claimed in claim 1, wherein the said rack rod (114) is enclosed within a rack bracket (104) and configured to extend into an extended housing (108) during forward displacement, wherein the said rack rod (114), the pinion (112), and the actuator (102) are mounted on a main structure (110).
8. The mechanism (100) as claimed in claim 1, wherein the said barrel closure unit (124) is in opening condition (200) during forward linear displacement of the actuator (102) and in closing condition (200a) during rearward linear displacement of the actuator (102).
9. The mechanism (100) as claimed in claim 1, wherein position of the crank shaft (122) and the pinion (112) remains locked independently during recoil movement and retaining movement of a barrel (126), wherein a locking mechanism in the rack rod (114) locks position of the pinion (112), wherein a closure locking arrangement of the barrel closure unit (124) locks position of the crank shaft (122).
10. A method of operation of a barrel closure unit (124), comprising steps of:
a forward displacement of an actuator (102) configured to obtain an opening condition (200) of the barrel closure unit (124);
a rearward displacement of the actuator (102) configured to obtain a closing condition (200a) of the barrel closure unit (124);
a disengaging movement (300) of an extended end (120) from a precise slot (118) of a pinion (112) during recoil movement of a barrel (126); and
an engaging movement (300a) of an extended end (120) within a precise slot (118) of a pinion (112) during end stroke of retaining movement of the barrel (126).