Description:TECHNICAL FIELD
[0001] The present disclosure relates to the field of mechanical safety devices for railway applications. In particular, the present disclosure provides a draft gear with shear off pins.

BACKGROUND
[0002] Vehicles, particularly rail vehicles such as locomotives, freight cars, goods wagons, passengers cars/coaches, boxcars, train engines, combo liners, etc., have draft gears attached at either ends. The draft gears absorb and dissipate energy due stresses/load caused to the vehicles on acceleration and deceleration. Draft gears are typically configured at the ends of the vehicles, or at the connections between adjacent cars, serve to cushion the vehicles from draw loads, buff loads, or impacts during collisions.
[0003] However, existing draft gears do not provide means to selectively allow engagement of appropriate load absorption and dissipation systems based on the amount of load applied thereto. Further, existing solutions do not allow the load thresholds for engaging the impact absorption devices to be selected by users. Additionally, the load thresholds may not be convenient to adjust after deployment of the device. The shearing elements may also not be capable of being replaced once they are sheared following an impact.
[0004] There is, therefore, a need for a draft gear with shear-off functionality. Particularly, there is a need for a draft gear having an adjustable load threshold, that is easier to maintain and replace, and allows for engagement of appropriate systems for absorption and dissipation of loads at a wide range of loads.

OBJECTS OF THE PRESENT DISCLOSURE
[0005] A general object of the present disclosure is to provide a draft gear with shear-off pins.
[0006] An object of the present disclosure is to provide a draft gear that disengages from a support structure to allow an impact absorption means to absorb a load when it exceeds a predetermined load threshold.
[0007] Another object of the present disclosure is to provide a draft gear that absorbs and dissipates energy from draw loads or buff loads.
[0008] Yet another object of the present disclosure is to provide a draft gear where the predetermined load threshold is adjustable based on requirements.

SUMMARY
[0009] Aspects of the present disclosure relate to the field of mechanical safety devices for railway applications. In particular, the present disclosure provides a draft gear with shear off pins.
[0010] An aspect of the present disclosure pertains to a draft gear. The draft gear includes a cushioning unit having a housing that accommodates a drawbar, and a cushioning means that absorbs draw loads and buff loads applied to the drawbar. The draft gear also includes a mounting flange that secures the housing to a support structure, a bush configured to allow the cushioning unit to pivot on a plane parallel to the ground, the bush being configured between the cushioning unit and the mounting flange, and one or more shear pins that secure the cushioning unit to the support structure through the mounting flange. The one or more shear pins are press fit into the housing through the housing. The one or more shear pins are configured to shear off when the draw loads or the buff loads applied to the drawbar may be greater than a predetermined load threshold, thereby allowing the drawbar to move along the length of the mounting flange.
[0011] In some embodiments, the one or more shear pins may include a slot between a first portion and a second portion thereof, the one or more shear pins shearing off at the slot and separating the first portion from the second portion when the draw loads or the buff loads applied to the drawbar may be greater than the predetermined load threshold.
[0012] In some embodiments, the draft gear may include one or more anti-friction disks that reduce friction between the cushioning unit and the mounting flange.
[0013] In some embodiments, the draft gear may include one or more holder plates that secures the bush to the mounting flange. In some embodiments, the one or more holder plates stabilize the position of the bush when loads perpendicular to the draw loads or the buff loads may be applied to the drawbar.
[0014] In some embodiments, the cushioning means may be a set of elastic elements that secure the drawbar to the housing, the set of elastic elements having elastic resilience to absorb draw loads and buff loads transmitted thereto through the drawbar.
[0015] In some embodiments, each elastic element in the set of elastic elements has an annular geometric profile. In some embodiments, the drawbar may include one or more grooves around which at least one elastic element from the set of elastic elements may be attached such that the set of elastic elements absorbs the draw loads and the buff loads applied to the drawbars.
[0016] In some embodiments, may include a vertical support structure that supports the drawbar such that the drawbar may be in a horizontal orientation with respect to a ground surface.
[0017] Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.
[0019] FIG. 1A illustrates an example representation of a draft gear, according to embodiments of the present disclosure.
[0020] FIG. 1B illustrates an example median cross-section representation of the draft gear, according to embodiments of the present disclosure.
[0021] FIG. 1C illustrates an example cross-section representation at a shear pin of the draft gear, according to embodiments of the present disclosure.
[0022] FIG. 1D illustrates an example isometric representation of the draft gear.
[0023] FIGs. 2A-2B illustrate example orthogonal and isometric views of the shear pins respectively, according to embodiments of the present disclosure.
[0024] FIGs. 3A-3D illustrate example cross-section views of the shear pins shearing off during impact, according to embodiments of the present disclosure.

DETAILED DESCRIPTION
[0025] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such details as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the present disclosures as defined by the appended claims.
[0026] As used herein, “substantially” means largely or considerably, but not necessarily wholly, or sufficiently to work for the intended purpose. The term “substantially” thus allows for minor, insignificant variations from an absolute or perfect state, dimension, measurement, result, or the like as would be expected by a person of ordinary skill in the art, but that does not appreciably affect overall performance.
[0027] Throughout the present disclosure, “attachment means” includes, but is not limited to, screws, nails, rivets, adhesives, magnets, hook and loop fasteners, hook and slot fasteners, interlocking elements, friction-grip releasable fasteners, fastening straps, and the like.
[0028] Embodiments explained herein relate to the field of mechanical safety devices for railway applications. In particular, the present disclosure provides a draft gear with shear off pins.
[0029] In an aspect, a draft gear includes a cushioning unit having a housing that accommodates a drawbar, and a cushioning means that absorbs draw loads and buff loads applied to the drawbar, a mounting flange that secures the housing to a support structure, and one or more shear pins that secure the cushioning unit to the support structure through the mounting flange. The one or more shear pins are configured to shear off when the draw loads or the buff loads applied to the drawbar may be greater than a predetermined load threshold, thereby allowing the drawbar to move along the length of the mounting flange.
[0030] Referring to FIGs. 1A-1D, a draft gear 102 with one or more shear pins 118 is illustrated. As shown, the draft gear 102 includes a mounting flange 104, a cushioning unit, and one or more shear pins, such as shear pins 118-1, 118-2 (collectively referred to as shear pins 118). The draft gear 102 may include a holder plate 114 corresponding to each of one or more bushes 112. The bushes 112 may be secured between the mounting flange 104 and the corresponding holder plate 114. In some embodiments, the cushioning unit may have a housing 106 that accommodates a drawbar 108, and a cushioning means such as an elastic element 110. The drawbar 108 may be movable along the length of the housing 106.
[0031] In some embodiments, the mounting flange 104 may be configured to a support structure. In some embodiments, the support structure may be any one of locomotives, rail cars, carriages or coaches, bumpers, buffer stops, and the like. The draft gears 102 may be installed on the support structures through the mounting flange 104 for absorbing draw or buff loads applied thereto. In some embodiments, the draw loads and the buff loads may be indicative of loads applied in a substantially horizontal direction with respect to a ground surface. The draw loads may be indicative of forces that cause structures to stretch or expand, and the buff loads may be indicative of forces that cause structures to compress or contract. The draft gear 102 may be configured to protect the support structure from the draw loads or buff loads applied thereto during acceleration or deceleration of the support structure, such as locomotives.
[0032] In some embodiments, the mounting flange 104 may be attached to the support structure using any one of the attachment means. In some embodiments, the mounting flange 104 may have a substantially cylindrical profile. In other embodiments, the mounting flange 104 may have a substantially cuboidal profile. The geometric profile of the mounting flange 104 may be suitably adapted to accommodate the drawbar 108 and the cushioning unit.
[0033] In some embodiments, the cushioning unit may be configured to absorb loads from the drawbar 108. In some embodiments, the drawbar 108 may be movable in a substantially horizontal direction with respect to the ground surface. At least a portion of the drawbar 108 may be configured to be inside the housing 106. When the mounting flange 104 is attached to a first support structure, the drawbar 108 may be moved by a second support structure. In an example, the first support structure may be a rail carriage and the second support structure may be a locomotive. In such examples, the locomotive may apply draw loads to the drawbar 108 when the locomotive accelerates, and the locomotive may apply buff loads to the drawbar 108 when it decelerates or brakes. Further, locomotives may apply both draw and buff loads during collisions. In some embodiments, the drawbar 108 may be a shaft having a first end thereof connected to the first support structure through the mounting flange 104 via the housing 106, and a second end thereof connected to the second support structure. The drawbar 108 may be attached to the first and second support structures by any one of the attachments means. The drawbar 108 may be made of rigid materials that allow mechanical loads, such as the draw and the buff loads, to be communicated/transmitted between the first and the second ends thereof.
[0034] In some embodiments, the cushioning unit may include the housing 106 that receives the drawbar 108. In some embodiments, the housing 106 may have a cylindrical profile. The geometric profile of the housing 106 may be suitably adapted to correspond to that of the mounting flange 104. The cushioning unit also may include a cushioning means that absorbs the draw and the buff loads from the drawbar 108. In some embodiments, the cushioning means may also secure the drawbar 108 to the housing 106. In some embodiments, the cushioning means may be indicative of the set of elastic elements 110. In some embodiments, the set of elastic elements 110 may be indicative of a spring set that resiliently bends/compresses to absorb the mechanical loads, and dissipates the absorbed load as heat. In some embodiments, the cushioning means may be a set of elastic elements 110 that secures the drawbar 108 to the housing 106, the set of elastic elements 110 having elastic resilience to absorb draw loads and buff loads transmitted thereto through the drawbar 108. In some embodiments, the elastic elements 110 may be bidirectionally resilient. In such embodiments, the elastic elements 110 may absorb the impact load when both draw and buff loads are communicated thereto through the drawbar 108.
[0035] In some embodiments, each elastic element in the set of elastic elements 110 may have an annular geometric profile. In some embodiments, the drawbar 108 may include one or more grooves around which at least one elastic element from the set of elastic elements 110 may be attached such that the set of elastic elements 110 absorb the draw loads and the buff loads applied to the drawbars 108. In such embodiments, the elastic elements may be indicative of O-rings configured around the drawbar 108. In some embodiments, the elastic elements 110 may be made of any one or combination of including, but not limited to, rubber, plastic, polymers, elastomers, and the like. In some embodiments, the composition, dimensions, and geometric profile of the elastic elements 110 may be suitably modified to obtain the desired elastic resilience for the user requirements.
[0036] In other embodiments, the cushioning means may be any one of including, but not limited to, hydraulic shock absorbers, pneumatic shock absorbers, springs, and the like. In such embodiments, the cushioning means may be configured at the first end of the drawbar 108. In some embodiments, the cushioning means may be configured to absorb loads up to a predetermined load threshold. When the impact load applied to the drawbar 108, which in turn is absorbed by the cushioning means, exceeds the predetermined load threshold, the impact load may be communicated to the mounting flange 104 via the housing 106. In such embodiments, the drawbar 108 may move the housing 106 along the length of the mounting flange 104.
[0037] In some embodiments, the draft gear 102 may include one or more holder plates 114 that secure a corresponding bush from one or more bushes 112 to the mounting flange 104. In some embodiments, the holder plates 114 may stabilize the position of the corresponding bushes 112 when loads perpendicular to the draw loads or the buff loads are applied to the drawbar 108. In some embodiments, the holder plate 114 may have a substantially circular contour. In some embodiments, the holder plate 114 may be attached to the mounting flange 104 by any one of the attachment means. In some embodiments, the bushes 112 may be secured between the holder plates 114 and the cushioning unit via the housing 106. While FIGs. 1A to 3D depict embodiments of the draft gear 102 having two holder plates and two corresponding bushes, it may be appreciated to those skilled in the art that the draft gear 102 may be suitably adapted to have any number of holder plates and bushes.
[0038] In some embodiments, the bushes 112 may have corresponding anti-friction disks 120 that reduce friction between the housing 106 and the mounting flange 104. In some embodiments, the anti-friction disks 120 may be annular disks coated with lubricants that reduce friction. The bushes 112 may lubricate and reduce friction between moving parts of the cushioning unit. In some embodiments, the bushes 112 may allow the drawbar 108 to be moved in a substantially horizontal direction with respect to the housing 106. In some embodiments, the bushes 112 may also allow the cushioning unit to be pivoted. The bushes 112 may allow the cushioning unit to be pivoted on a plane substantially parallel to the ground. In examples where the first and the second support structures indicative of adjacent train cars are connected by the draft gear 102, the cushioning unit may pivot to allow the train cars to turn or change the angle formed therebetween with respect to the plane parallel to the ground. In such examples, the train cars may turn with respect to each other due to curvatures of the track. In some embodiments, the drawbar 108 may be pivoted in plane substantially parallel to the ground surface. In other embodiments, the drawbar 108 may be pivoted in a plane substantially perpendicular to the ground surface. In some embodiments, the bushes 112 and the holder plate 114 may stabilize the housing 106 to allow the drawbar 108 to be rotatable.
[0039] In some embodiments, the draft gear 102 may include a vertical support structure 116 that supports the drawbar 108. The vertical support structure 116 may be configured to support the drawbar 108. In some embodiments, the vertical support structure 116 may orient the drawbar 108 in a substantially horizontal orientation with respect to the ground surface.
[0040] Referring to FIGs. 2A-2B, the structural design of the shear pins 118 is illustrated. As shown, the shear pins 118 may include a slot 202 between a first portion 201 and a second portion 203 thereof. While FIGs. 2A-2B show embodiments where the shear pins 118 are substantially cylindrical with the slot 202 in the middle of the shear pins 118 having a tapering profile, it may be appreciated by those skilled in the art that the shear pins 118 may be any one or combination of including, but not limited to, tapering shear pins, step shear pins, helical shear pins, sloted shear pins, hollowed shear pins, notched shear pins, grooved shear pins, frangible shear pins, and the like. The shape of the slot may be suitably adapted based on geometric profile and dimensions of the shear pins 118. In some embodiments, the first portion 201 and the second portion 203 of the shear pins 118 may be connected at the slot 202. In some embodiments, the first portion 201 and the second portion 203 may be connected by the slot 202 through any one of the attachment means. In other embodiments, the first portion 201 may be integrally connected to the second portion 203 at the slot 202.
[0041] In some embodiments, the shear pins 118 may be press fitted into the housing 106 through the bushes 112 and the holder plates 114. In such embodiments, the first portion 201 of the shear pins 118 may be substantially inside the bush 112 and the second portion 203 may be substantially inside the housing 106, as shown in FIG. 3A. In some embodiments, the bushes 112 and the housing 106 may have cavities that accommodate the shear pins 118. Cross-sectional diagonal of the cavities may be less than or equal to cross-sectional diagonals shear pins 118, thereby allowing the shear pins 118 to securely fit into the cavities. In other embodiments, the shear pins 118 may be inserted into the housing 106 and the bushes 112 through means including, but not limited to, hammering, drilling, screwing, and the like.
[0042] In some embodiments, the draft gear 102 may secure the cushioning unit to the support structure through the mounting flange 104 using the shear pins 118. In some embodiments, the shear pins 118 may prevent the housing 106 of the cushioning unit from moving with respect to the mounting flange 104, while allowing the drawbar 108 to move along the length of the housing 106 to the extent allowed by elastic resilience of the cushioning means. The shear pins 118 may lock the position of the housing 106.
[0043] In some embodiments, the shear pins 118 may be configured to shear off at the slot 202, and thereby separate the first portion 201 from the second portion 203, when the draw loads or the buff loads applied to the drawbar 108 may be greater than the predetermined load threshold. In some examples, the impact load may breach the predetermined threshold during a crash or a collision with other rail vehicles or obstacles.
[0044] When the draw loads or the buff loads are less than the predetermined load threshold, the drawbar 108 may communicate the force to the cushioning means, and the cushioning means may absorb the impact loads. However, when the impact load is greater than the impact load threshold, such as loads shown in FIG. 3B to 3C, the impact load may also be greater than the elastic resilience of the cushioning elements. In some embodiments, the draw/buff loads may exceed the threshold during collisions or accidents. In such embodiments, the impact load may be communicated to the housing 106 from the drawbar 108 through the cushioning means. In some embodiments, the housing 106 may transmit the impact load therefrom to the shear pins 118. When the impact load is greater than the predetermined load threshold, the impact load may be sufficient to shear off the shear pins 118 at the slot 202, as shown in FIGs. 3B and 3C. In such embodiments, shearing of the shear pins 118 may allow the cushioning unit, and the components associated therewith, to move along the length of the mounting flange 104.
[0045] In some embodiments, the cushioning unit may move beyond the length of the mounting flange 104, as shown in FIG. 3D. In some embodiments, the cushioning unit may move and engage with other shock-absorbing elements on the support structure. In some examples, during a crash or a collision, the cushioning unit may cause the shear pins 118 to be sheared off to cut the connection between the first and second support structures (such as two train cars). In such examples, the cushioning unit may move beyond the length of the mounting flange 104, and move into the body of the vehicle. By moving into the body of the vehicle, the draft gear 102 may allow the support structure to use impact absorption means, such as side crash buffers or anti-climbers, to reduce the impact intensity on the passengers and control the damage levels. The impact absorption means of the frontal train car, after pushing the draft gear 102 into the body of the rear train car, may engage with the impact absorption means of the rear train car.
[0046] In some embodiments, the operationality of the draft gear 102 may be restored following shear off events as described above. In such embodiments, if the components of the draft gear 102, except for the shear pins 118, are operational, the shear pins 118 may be may be replaced after shearing to allow the draft gear 102 to maintain operationality thereof. To replace the shear pins 118, the first portion 201 of the shear pins 118 placed in the holder plates 114 or the bushes 112 may be removed therefrom. The second portion 203 of the shear pins 118 remaining on the housing 106 may be removed after dismantling the draft gear 102. In some embodiments, the holder plates 114 may be removed from the mounting flange 104, by detaching the attachment means, to provide access to the housing 106. The second portion 203 of the shear pins 118 may then be removed from the housing 106. In some embodiments, the shear pins 118 may be replaced after aligning the drawbar 108 and the housing 106 with the bushes 112 and the holder plate 114. In some embodiments, the elastic elements 110 may also be replaced following the shearing off events. The elastic elements 110 and/or the shear pins may also be regularly inspected and replaced during maintenance.
[0047] The shear pins 118 as described in the present disclosure may allow the predetermined load threshold to be customized based on the use requirements. In some embodiments, the materials used to manufacture the shear pins 118 may be suitably adapted to change the rigidity, and correspondingly the force required to shear off, the shear pins 118. In some embodiments, the geometric profile of the shear pins 118 may be suitably adapted based on requirements. In some embodiments, the shear pins 118 may have a substantially cylindrical profile. In other embodiments, the shear pins 118 may have a substantially cuboidal profile.
[0048] In some embodiments, the number of shear pins 118 configured to the draft gear 102 may be adapted based on use requirements. In some embodiments, the number of shear pins 118 may be increased or decreased to correspondingly increase or decrease the predetermined load threshold. While FIGs. 1A to 3D depict embodiments where the draft gear 102 has up to 8 shear pins 118, it may be appreciated by those skilled in the art that the number of shear pins 118 may be suitably adapted based on the requirements. The orientation and arrangement patterns of the shear pins 118 with respect to the housing 106 may also be suitably adapted based on use requirements to provide equi-distribution of force throughout the cushioning unit. In some embodiments, the shear pins 118 may be configured perpendicularly into the housing 106. In other embodiments, the shear pins 118 may be inserted into the housing 106 at an angle. Further, in some embodiments, an equivalent number of shear pins 118 may be configured to opposing portions, such as top and bottom, of the housing 106.
[0049] The draft gear 102 may be suitable for vehicular applications, particularly rail applications, where loads and stresses below a predetermined load threshold experienced during normal operation of the vehicles. The acceleration and deceleration of vehicles may cause loads to be applied to the drawbar 108, which may be absorbed and dissipated by the cushioning unit. The draft gear 102 may also be adapted to provide enhanced safety to the vehicle during crashes or collisions by engaging additional, and more sturdier, shock-absorption elements. Such shock-absorption elements may be capable of withstanding loads above a predetermined threshold, such as those during crashes or collisions, thereby enhancing safety of occupants of the vehicle and also preventing the vehicle from derailing. When loads greater than the predetermined load threshold is applied to the draft gear 102 of the present disclosure, the draft gear 102 shears off the shear pins 118, thereby allowing the drawbar 108 to move and engage the shock-absorption elements. Hence, the draft gear 102 of the present disclosure provides for load absorption and dissipation functionality both during normal operation, and during crash or collision events.
[0050] While the foregoing describes various embodiments of the disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof. The scope of the disclosure is determined by the claims that follow. The disclosure is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

ADVANTAGES OF THE PRESENT DISCLOSURE
[0051] The present disclosure provides a draft gear with shear-off pins.
[0052] The present disclosure provides a draft gear that disengages from a support structure to allow an impact absorption means to absorb an impact/load that exceeds a predetermined load threshold.
[0053] The present disclosure provides a draft gear that absorbs and dissipates energy from draw loads or buff loads.
[0054] The present disclosure provides a draft gear where the predetermined load threshold is adjustable based on requirements.
[0055] The present disclosure provides a draft gear with equi-distributed shear pins that allows for shear-off functionality at a diverse range of loads.

, Claims:1. A draft gear (102), comprising:
a cushioning unit having a housing (106) that accommodates a drawbar (108), and a cushioning means that absorbs draw loads and buff loads applied to the drawbar (108);
a mounting flange (104) that secures the housing (106) to a support structure;
a bush (112) configured to allow the cushioning unit to pivot on a plane parallel to the ground, the bush (112) being configured between the cushioning unit and the mounting flange (104); and
one or more shear pins (118) that secure the cushioning unit to the support structure through the mounting flange (104), wherein the one or more shear pins (118) are press-fit into the housing (106) through the bush (112), and wherein the one or more shear pins (118) are configured to shear off when the draw loads or the buff loads applied to the drawbar (108) is greater than a predetermined load threshold, thereby allowing the drawbar (108) to move along the length of the mounting flange (104).

2. The draft gear (102) as claimed in claim 1, wherein the one or more shear pins (118) comprise a slot (202) between a first portion (201) and a second portion (203) thereof, the one or more shear pins (118) shearing off at the slot (202) and separating the first portion (201) from the second portion (203) when the draw loads or the buff loads applied to the drawbar (108) is greater than the predetermined load threshold.

3. The draft gear (102) as claimed in claim 1, comprising one or more anti-friction disks (120) that reduce friction between the cushioning unit and the mounting flange (104).

4. The draft gear (102) as claimed in claim 1, comprising one or more holder plates (114) that secure the bush (112) to the mounting flange (104), wherein the one or more holder plates (114) stabilize the position of the bush (112) when loads perpendicular to the draw loads or the buff loads are applied to the drawbar (108).

5. The draft gear (102) as claimed in claim 1, wherein the cushioning means is a set of elastic elements (110) that secures the drawbar (108) to the housing (106), the set of elastic elements (110) having elastic resilience to absorb the draw loads and the buff loads transmitted thereto through the drawbar (108).

6. The draft gear (102) as claimed in claim 5,
wherein each elastic element in the set of elastic elements (110) has an annular geometric profile, and
wherein the drawbar (108) comprises one or more grooves around which at least one elastic element from the set of elastic elements (110) is attached such that the set of elastic elements (110) absorbs the draw loads and the buff loads applied to the drawbar (108).

7. The draft gear (102) as claimed in claim 1, comprising a vertical support structure (116) that supports the drawbar (108) such that the drawbar (108) is in a horizontal orientation with respect to a ground surface.