Claims:WE CLAIM:
1. A dual interlocking system (100) for shuttle transmission in tractors, comprising:
a transmission housing, comprising atleast four speed gears and forward(F) & reverse(R) gears and high(H) and low(L) range gears to operatively engage with the said speed gears ;
characterized in that the system comprises, at least four gear shifting rails, including a first rail (101) for engaging 1st and 2nd gears, a second rail (102) for engaging 3rd and 4th gears, a third rail (103) for the forward and reverse gears and a fourth rail (104) for engaging high and low speed gears, horizontally assembled adjacent to one another and run parallel to each other;
at least three gear shift levers operatively connected to the shift rails for selecting the gears;
at least three ball interlocks (105a, 105b and 105c) operatively positioned in between the said gear shifting rails (101, 102, 103, 104);
a ball retainer (106) assembled in transmission housing and lugs are positioned between rails to retain the ball interlock (105a, 105b and 5c) in a predefined position;
a pin interlock (107) and operatively positioned in a third rail (103), to assemble pin interlock (107) in third rail (103), a slot portion (110a) on the third rail (103) adjacent to the forward position on the said pin lock retainer (107a) for seating the pin lock, a plurality of holes provided to retain the ball interlock within the ball retainer(106);
a groove (108) for first interlock mechanism, provided in first rail (101) and a second rail (102), groove (109) provided in second rail (102) and groove (110) provided in both side of third rail (103) for second interlock mechanism and also groove (111) provided in fourth rail (104);
a gear shifting coupler; a plurality of gear shifting forks to connect the said gear shift rails to gear shifting lever to the shift fork by linkages; wherein the speed gears are locked in the high ranges when reverse gears engage ;
wherein the system is configured for a first interlocking mechanism for locking the speed gears 3 and 4, and a second interlocking mechanism wherein speed gears 3, 4, High and Reverse gear is locked,
wherein in the first interlocking, the system:
i) engages the speed gears at the first and second position and locks the speed gears at third and fourth position or
ii) engages speed gears at the third and fourth position and locks the speed gears at the first and second position; and
wherein in the second interlock mechanism, the system:
i) engages the high range gears and speed gears at the third and fourth position and locks the reverse gears ;
ii) engages the high and reverse gears and locks the speed gears at the third and fourth position (3rd and 4th), and
iii) engages the reverse gears and speed gears at the third and fourth position and locks the high range gears.

2. The dual interlocking system for shuttle transmission in agricultural tractors as claimed in claim 1, wherein the said system locks the speed gears in the third and fourth position in high ranges in the reverse direction.

3. The dual interlocking mechanism for shuttle transmission in agricultural tractors as claimed in claim 1, wherein the said gear shifting levers comprising of : first gear shifting lever (112) positioned at the right side of tractor to engage the said speed gears ; a second gear shifting lever(113) positioned on the left of the tractor to engage the high and low range gears ; a third gear shift lever(114) positioned on the instrument panel of the tractor to engage the forward and reverse gears

4. The dual interlocking system for shuttle transmission in agricultural tractors as claimed in claim 1, wherein the said gear shifting rails comprises: a first rail (101) having first and second position for engaging 1st second gears ;a second rail (102) having third and fourth positions for engaging 3rd and 4th gear; a third rail(103) having and forward and reverse ranges, fourth rail (104) having, high and low ranges wherein the upon operation, the shift lever selects the gear and the rail moves a fork that’s attached to gear or sleeve.

5. The dual interlocking system for shuttle transmission in agricultural tractors as claimed in claim 1, wherein during the first interlock mechanism, ball interlock (105a) assembled within the ball retainer(106) between third and fourth positions to avoid double engagement of the gears.

6. The dual interlocking system for shuttle transmission in agricultural tractors as claimed in claim 1, wherein upon engagement of the ball interlock (105b and 105c), pin interlock(107) is locked between the said ball interlocks locking the gears in high ranges in the reverse direction.

7. The dual interlocking system for shuttle transmission in agricultural tractors as claimed in claim 1, wherein the said pin interlock (107) is oval.

8. The dual interlocking system for shuttle transmission in agricultural tractors as claimed in claim 1, wherein the slot for pin interlock is an oval shaped slot configured to engage the pin interlock (107).

9. A method of operation of the dual interlocking system for shuttle transmission in agricultural tractors, the said method comprising the steps of:
operator moving the gear shift lever to select the gear;
movement of the rail corresponding to the fork attached to gear or sleeve;
assembling the ball interlocks in between the rails in a predefined position upon the shifting of lever, causing slot machining of the pin interlock in the forward and reverse rails in the hole portion to lock the speed gears in the third and fourth position in the reverse direction in high ranges, implemented as a first interlock mechanism for engaging speed gears 1, 2 and locking of speed gears 3rd and 4th, and
a second interlocking mechanism for engaging high gear H, 3rd and 4th gears and locking reverse gear, engaging high H gear, and reverse with locking speed gears 3rd and 4th, and engaging 3rd , 4th and reverse and locking high gear.
‘
10. The method of operation of the dual interlocking system for shuttle transmission in agricultural tractors as claimed in claim 9, wherein the said system locks the speed gears in the third and fourth position in high ranges in the reverse direction

11. The method of operation of the dual interlocking system for shuttle transmission in agricultural tractors as claimed in claim 9, wherein in the first interlock mechanism during the engagement of the first rail (101) in the 1st and 2nd, ball interlock (105a) seats on groves (109) of second rail (102) in 3rd and 4th gear locking it and the said second rail (102).

12. The method of operation of the dual interlocking system for shuttle transmission in agricultural tractors as claimed in claim 9, wherein in the first interlock mechanism during the engagement of the second rail (102) in the 3rd, 4th gear, ball interlock (105 a) seats on groves (108) of first rail (101) in the first and second position locking the gear shifting of 1st and 2nd gear in said first rail (101).

13. The method of operation of the dual interlocking system for shuttle transmission in agricultural tractors as claimed in claim 9 , wherein engaging high gear H, 3rd and 4th gears and locking reverse gear comprises steps::
movement of second rail (102) to 4th gear position;
movement of ball interlock (105b) towards the third shift rail 103;
movement of fourth rail H-L (104) to position H i..e towards left and ball 105c moves towards the third rail F-R (103).
movement of ball interlock (105c) towards the said third rail (103) having forward and reverse ranges;
locking of the pin interlock (107) in between the ball interlocks (105a and 105c), disallowing the in reverse position of third rail, and
wherein the pin interlock is positioned after ball slot machining in third rail 103, allowing movement to forward position.

14. The method of operation of the dual interlocking system for shuttle transmission in agricultural tractors as claimed in claim 8, wherein engaging high H gear, and reverse with locking speed gears 3rd and 4th in the second interlock mechanism comprises steps:
i) movement of the said fourth rail in the high range position and movement of ball interlock (105c) towards the third rail(103) in the forward and reverse ranges,
ii) movement of the said third rail (103) to the reverse range position thereby moving the pin interlock (107) and pushing the ball interlock (105b) and interlocking with groove (110) of the second rail (102), and
iii) seating of ball interlock (105b) in groove (109) locking 3rd and 4th gear.

15. The method of operation of the dual interlocking system for shuttle transmission in agricultural tractors as claimed in claim 9 , wherein engaging 3rd , 4th and reverse and locking high gear in second interlock mechanism comprises steps:
i) engaging the second rail to 4th gear position and moving ball interlock (5b) towards the third rail (103) in the forward and reverse ranges;
ii) movement of the said third rail in the reverse position thereby moving the pin interlock(107) to push the ball interlock (105c) to groove (111), and
iii) positioning of the ball interlock (5c) in groove (111) of fourth rail (104) having high and low ranges thereby locking in the high range position, and allowing low range gear shifting

-SD-
Kalyan Jhabakh (IN/PA-830)
Agent for Applicant
, Description:DUAL INTERLOCK SYSTEM FOR SHUTTLE TRANSMISSION IN TRACTORS AND A METHOD THEREOF
FIELD OF INVENTION

The present invention generally relates to agricultural vehicle speed transmission system, in particular the present invention is relating to a dual interlock system for shuttle transmission to lock the vehicle travelling speed in reverse direction more than 20KMPH.

BACKGROUND OF INVENTION
Generally, tractors with shuttle transmission is having equal number of forward and reverse speeds. For example, 8X8 shuttle transmission means 8 FWD and 8 REV speeds. Usually a shuttle system tractor, Hand operated gear shift lever is used to control the forward / reverse speed of vehicles. For agricultural tractors maximum travelling speed in in the range of approx. 38kmph at rated engine rpm. Since tractors are having shuttle transmission with equal number of forward / reverse speed, maximum reverse travelling speed of tractor is also having approx. 38 kmph at rated engine rpm.

Tractors that are having shuttle transmission feature which is having equal forward/ reverse gears are used in wide application range. In MF brand tractors, 8x8 (8F/8R) shuttle transmission feature is already in production in the global and domestic market. In this tractors shuttle transmission, gear is positioned in three sections. One set of Forward / Reverse gears, 4 speed gears (speed gears 1-2-3-4) and High-Low range gears. In 8x8 shuttle transmission following the gear shifting ranges such as, in the forward range FL1, FL2, FL3, FL4, FH1, FH2, FH3, FH4 and in the reverse range RL1, RL2, RL3, RL4, RH1, RH2, RH3, RH4 are available.

In this gear box, to get above shifting ranges 4 set of rails and fork used. In order to avoid double gear engagement of speed gears (1-2-3-4 gears) rails are having inter lock mechanism and other section rails are independently placed and thus there is no relation or lock between other sections. Since there is no relation or lock between each gear section, operator can able to shift the all eight position of gears in forward and reverse gears and tractor reaches maximum travelling speed in both forward and reverse direction.

During operations driver may shift the gear position directly to reverse gear of the transmission at high speed which become difficult to control the vehicle and also this may cause the series accidents and vehicle impairment. Therefore, it is particularly important to add the additional lock mechanism in the gear shifting arrangement. Further, selection of reverse mode at higher gear ratios is also possible during such lever shift. It is apparent that this large and over speed gear condition could be detrimental to the vehicle operation leading to safety critical concerns. Therefore, in order to maintain safety during such situations, during reverse gear selection tractor it is advisable maximum travel speed should not exceed 20 kmph at rated engine RPM. Hence there need to be maintain a standard requirement such that during reverse gear, that is above 20 kmph gear shifting position should be intentionally locked.

Indian 3614/CHE/2014 discloses an interlock mechanism for forward / reverse gear levers and clutch pedal interlocked to ensure the F/R gear lever shifting after pressing of clutch pedal in tractors. That includes a locking plate operatively connected to a gear shifting lever, a spring loaded plunger operatively connected to the locking plate and a clutch pedal lever. The locking plate is configured to lock the movement of gear shifting lever and the plunger is configured to release the locking plate on engagement of the clutch pedal lever. In the said arrangement the locking plate 116 includes an opening 116a for receiving the FR gear shifting lever 118 and a plurality of slots 116b for receiving the plunger 108. Once the locking plate 116 is welded with the FR gear shifting lever 118, movement of the FR gear shifting lever 118 results in the movement of the locking plate. The said interlock system is located outside the tractor especially at the clutch pedal area in bulk head.

US4726250A discloses a shift rail lock-out mechanism suitable for vehicles such as cars and trucks that is directed towards a manual transmission having left and right pairs of shift rails arranged in a symmetrical manner about a medial plane. A lock-out frame member defines a rectangular-shaped opening through which said pairs of rails extend for individual reciprocal travel therein such that a pair of left and right shuttle blocks are supported in the frame member opening such that each shuttle block is captured between its associated pair of rails and adapted to slide relative thereto. The frame member includes left and right internal locking edges while each shuttle block has inner and outer locking edges. The locking edges cooperate with opposed camming recesses in the rails for concurrent transverse movement to insure travel of only one rail at a time during the shifting operation. In the said locking mechanism in order to move the reverse gear rail for engage the rev gear, all the remaining three rails will be locked.

EP0331278A2 discloses a shift rail interlock mechanism (18) for a transmission having a plurality of parallel shift rails (16a,16b,16c) is operative to inhibit movement more than one shift rail from its neutral position at a given time. In the said mechanism separate interlock pin 31,32) is slidably mounted within the aperture between each pair of shift rails where the interlock pins is provided with tapered end portions (31b,31c) defining end surfaces (31d,31e) engageable with end surfaces of adjacent pins. Similar to the conventional gear box mechanism, whenever there is an engagement or disengagement of gears possess the technical difficulty that the remaining gear should locked in neutral position for avoiding double engagement. Further, in the three rail arrangement, the movement of two rails is restricted and the system allows one rail movement.

CA785494A relates to a vehicle transmission control deals with parking brake function by gear levers. In this transmission gear are positioned in four speed gears and three range gears and two gear levers position in tractor. One for shift the speed gears 1-2-3-4 and another one is used to shift the range gears L-M-H & P (Parking brake). In this tractor parking brake achieved from engine by engagement of transmission gear to wheel. Interlock mechanism made to ensure engagement of speed gears when range shifting gear lever in P (Parking brake) position.

CN104896086A relates to gear shifting mechanism in single rail arrangement. In this arrangement two gear shifting fork assembled in single rails. To avoid the movement of two fork in same time, interlocking pin assembled in rail hole. This pin will ensure any one fork movement in same time. In the said interlocking mechanism an interlocking member that is at least partially received within the one interlocking passage may extend to the first recess or the first when the first gear engagement device or the second gear engagement device is respectively in neutral inside of the two notches.

CN104455403A discloses a separate interlocking mechanism for reverse gear of transmission with one operating shafts and six gears in which addressees the problem that interlocking cannot be achieved at the reverse gear due to the fact that an existing transmission with one operating shafts and six gears is limited by space and gear choosing positions. A gear shifting plate is fixed to a reverse gear shifting fork, a gear shifting groove is formed in the gear shifting plate, a locking pin inserted into the gear shifting groove is arranged in the gear shifting groove. Further, a compression spring plug screw is arranged on a casing, and a locking spring is connected between the compression spring plug screw and the locking pin. In the said interlocking mechanism also the interlock pin assembled in rev gear fork but whenever reverse gear moves interlock pin lock the other 6 forward gears. The whole arrangement increases the complexity of the mechanism.

The prior art references mentioned hereinabove are mostly shuttle transmission systems that has equal forward or reverse speed for four-rail transmission systems that are assembled in horizontal position. Such transmission systems, to avoid double engagement in speed gears (1-2-3-4) interlocking balls provided for ensure the one gear engagement in four speed gears and remaining gears three gears are neutral. Further in tractors conventionally other gears / shift levers especially forward/reverse and high/low are independent and no locking mechanism available. Since there is no interlocking between Speed gears, F/R gears and High-Low range gears, tractor reaches maximum travelling speed in both forward and reverse direction.
Hence, there is a need in the art that can provide an interlocking system which prevents high range reverse gear operation of a vehicle and limiting the vehicle speed in reverse direction. Therefore, the present invention provides a dual lock system such that in addition with regular interlock mechanism an additional interlock mechanism in gear shift rails prevents the selective reverse speed in selective gears. I.e. HR3, HR4
OBJECTIVES OF THE INVENTION
The main objective of the instant invention is to provide a dual interlock system for shuttle transmission to lock the vehicle travelling speed in the reverse direction in high ranges of more than 20 kmph.
Another objective of the instant invention is that to provide a dual interlock system where an additional interlock mechanism other than the regular interlock mechanism in gear shift rails which prevents the selective reverse speed in selective gears. I.e. HR3, HR4
Another objective is to provide a slot in Rail F/R to assemble the oval shape interlock pin, also three lugs in retainer to support the three interlocking balls assembled in transmission housing for locking of any condition high range reverse gear in 3rd & 4th gears.
It is yet another object of the present invention to provide a method of working of the interlock system as embodied in the present invention.
SUMMARY OF THE INVENTION

The present invention discloses a dual interlocking system for shuttle transmission in agricultural tractors comprising of:
a transmission gear housing, wherein the said transmission gear unit having at least four speed gears (1-2-3-4) and high(H) / low(L) range gears and in forward(F) / reverse(R) gears to operatively engage with the said speed gears comprising: at least four gear shifting rails, including a first rail (101) a second rail (102) a third rail (103) and a fourth rail (104) horizontally assembled adjacent to each other; at least three gear shift levers operatively connected to the shift rails for selecting the gears; at least three ball interlocks (105a, 105b and 105c) operatively positioned in between the said gear shifting rails; a pin interlock operatively positioned on the second rail in the forward & reverse ranges; a ball retainer (106) operatively connected to retain the said ball interlock (105a, 105b and 105c) in a predefined position; a pin interlock retainer (107a) to retain the pin interlock (107) in a predefined position; a hole portion(108) on the second rail adjacent to the forward position on the said pin lock retainer(107a) for seating the pin lock; a plurality of groves provided to retain the ball interlock within the ball retainer; a plurality of holes provided on the ball retainer to retain the ball interlock ; a gear shifting coupler; a plurality of gear shifting forks to connect the said gear shift rails to gear shifting lever to the shift fork by linkages; to lock the reverse gear in high range condition of 3rd / 4th gears.
In this transmission consist of two interlock mechanism, whereby during the first interlock mechanism,
i) engages the speed gears at the 1st or 2nd position and locks the speed gears at 3rd and 4th gear position.
ii) engages speed gears at the 3rd or 4th position and locks the speed gears at the 1st and 2nd gear position; and
during the second interlock mechanism,
i) engages the high range gears and speed gears at the 3rd / 4th position and locks the reverse gears ; or
ii) engages the high and reverse gears and locks the speed gears at the 3rd and 4th position or
iii) engages the reverse gears and speed gears at the 3rd and 4th position and locks the high range gears
The present invention further discloses a method of operation of the dual interlocking system for shuttle transmission in agricultural tractors, the said method comprising the steps of:
i) operator moving the gear shift lever to select the gear
ii) movement of the rail corresponding to the fork attached to gear or sleeve.
iii) assembling the three interlocking balls in between three rails in a predefined position upon the shifting of lever
iv) slot machining provided in forward and reverse rails and oval shape pin interlock assembled in rail slot portion to lock the speed gears in the third and fourth position in the reverse direction in high ranges

BRIEF DESCRIPTION OF DRAWINGS
Fig 1(a) is the representation of the gear shifting rails of the interlocking system in neutral position
Fig 1(b) is an illustration of the components of the interlocking system in neutral position
Fig 1(c) is the representation of the gear shifting rails of the interlocking system in neutral position, ball interlock, pin interlock, and pin lock retainer.
Fig 2(a) illustrates a detailed view of the interlocking system in the neutral position
Fig 2(b) illustrates an enlarged view of the interlocking system in the neutral position
Fig 3 (a) is an illustration of the first interlocking mechanism during the engagement of 1st gear and locking(circled in the figure) of the 3rd / 4th gear.
Fig 3(b) represents an enlarged view of the first interlocking mechanism during the engagement of 1st gear and locking of the 3rd / 4th gear.
Fig 4(a) is an illustration of second interlocking mechanism during the engagement of high gear, 4th gear and locking(circled in the figure) of reverse gear.
Fig 4(b) represents an enlarged view of the second interlocking mechanism during the engagement of high gear, 4th gear and locking of reverse gear.
Fig 5(a) is an illustration of second interlocking mechanism during the engagement of high gear, reverse gears and locking(circled in the figure) of 3rd / 4th gear.
Fig 5(b) represents an enlarged view of second interlocking mechanism during the engagement of high gear, reverse gears and locking of 3rd / 4th gear.
Fig 6(a) is an illustration of second interlocking mechanism during the engagement of 4th gear, reverse gear and locking(circled in the figure) of high gear.
Fig 6(b) represents an enlarged view of second interlocking mechanism during the engagement of 4th gear, reverse gear and locking of high gear.
Fig 7 Illustrates the General arrangement of 8X8 shuttle transmission with positioning of rails, fork, shift mechanism and interlocking mechanism.

DETAILED DESCRIPTION OF THE INVENTION

The present invention as embodied by an “A dual interlock mechanism for shuttle transmission in agricultural tractors and a method thereof” succinctly fulfills the above-mentioned need[s] in the art. The present invention has objective[s] arising as a result of the above-mentioned need[s], said objective[s] having been enumerated hereinabove.
The following description is directed to “A dual interlock mechanism for shuttle transmission in agricultural tractors and a method thereof”. In as much as the objective(s) of the present invention are enumerated, it will be obvious to a person skilled in the art that, the enumerated objective(s) are not exhaustive of the present invention in its entirety, and are enclosed solely for the purpose of illustration. Further, the present invention encloses within its scope and purview, any structural alternative(s) and/or any functional equivalent(s) even though, such structural alternative(s) and/or any functional equivalent(s) are not mentioned explicitly herein or elsewhere, in the present disclosure. The present invention therefore encompasses also, any improvisation[s]/modification[s] applied to the structural alternative[s]/functional alternative[s] within its scope and purview. The present invention may be embodied in other specific form[s] without departing from the essential attributes thereof.

Furthermore, the terms and phrases used herein are not intended to be limiting, but rather are to provide an understandable description. Throughout this specification, the use of the word "comprise" and variations such as "comprises" and "comprising" may imply the inclusion of an element or elements not specifically recited.

Embodiments of the present invention provide a Novel dual interlock mechanism for shuttle transmission to lock the vehicle travelling speed more than 20 kmph in reverse direction. In various embodiments, the disclosed shift interlock assembly may be useful for this purpose (and others). This novel, twin or dual interlock mechanism can be implemented to lock the reverse gear for any vehicle. For exemplary purposes the invention is described for an agricultural vehicle particularly a tractor.

The present invention in various embodiments relates to dual interlock system comprising of one or more shift rails that interlock and the transmission having a plurality of shift rails which are shiftable along spaced apart and parallel axes. Although the shift rails are generally two or more, exemplary embodiments of the present invention disclose at least four shift rails. The shift rail interlock mechanism is utilized in conjunction with a transmission.
Referring to figures 1-7, an embodiment of the present invention provides a dual interlocking system for shuttle transmission in agricultural tractors comprising:
a transmission housing, wherein the said transmission gear unit having at least four speed reference is drawn to Figure 1a, 1b, and 1c, a gear (1-2-3-4), forward (F) / reverse (R) gears and high (H) / low (L) range gears to operatively engage with the said speed gears. The system comprises, at least four gear shifting rails, comprising, in reference to Figure 1a first rail (101) for engagement of 1st and 2nd gears, a second rail (102) for engagement of 3rd and 4th gears, a third rail (103) for the forward and reverse gears and a fourth rail (104) for engaging high and low speed gears, horizontally assembled adjacent to one another and run parallel to each other; at least three gear shift levers operatively connected to the shift rails for selecting the gears; in reference to figure 1b and 1c, at least three ball interlocks (105a, 105b and 105c) operatively positioned in between the said gear shifting rails; a ball retainer (106) assembled in transmission housing and lugs are positioned between rails to retain the ball interlock (105a, 105b and 5c) in a predefined position; pin interlock (107) may be oval in shape preferably and operatively positioned in a third rail (103), to assemble pin interlock (107) in third rail (103), a oval shape slot portion (108) on the third rail adjacent to the forward position on the said pin lock retainer(107a) for seating the pin lock, a plurality of holes provided to retain the ball interlock within the ball retainer; To ensure working of first interlock mechanism groove (108) provided in first rail (101) and a second rail (102) and working of second interlock mechanism groove (109) provided in second rail (102) and groove (110) provided in both side of third rail (103) and also groove (111) provided in second rail (104); a gear shifting coupler; a plurality of gear shifting forks to connect the said gear shift rails to gear shifting lever to the shift fork by linkages; wherein the speed gears are locked in the high ranges when reverse gears engage
Pin interlock is provided as oval in shape, but it can also be made of other shapes and should not be construed to confine the shape to oval alone. Oval shaped pin interlock (107) is an exemplary embodiment.
In a particular embodiment, the vehicle gear shifting rails are positioned in reference to the user/ driver position (figure 1a) from left to right, High low rail (104), FWD/REV rail (103), 3-4 Rail (102), 1-2 rail (101). With above rail position, the lock between Reverse gears are provided in high range of 3-4 gear rails and this lock will not allow for gear shifting of RH3 and RH4 gear shifting position

The interlock mechanism of the dual interlock system for shuttle transmission for locking in reverse direction is described by more than one embodiments, which covers:
1. A first interlock mechanism wherein the 1st or 2nd gears are engaged and the 3rd and 4th are locked.
2. Similarly, The 3rd or 4th gear are engaged and 1st and 2nd gears are locked.
whereby during the first interlock mechanism,
i) engages the speed gears at the 1st of 2nd position (101) and locks the speed gears at 3rd and 4th position (Figure 3a, 3b). This is achieved as the shift rail 101 moves to position of gear 1, depicted by (1) in figure 3(a), the ball 105a moves and sits on shift rail 102 groove (108), thus the gear shifting of the 3rd and 4th gear is disabled or not allowed.
ii) engages speed gears at the 3rd or 4th position and locks the speed gears at the 1st and 2nd position by movement of the ball 105a and positioned on shift rail 101 groove (108) and disallowing of the gear shifting of the 1st and 2nd gear associated with the shift rail 101.
In another embodiment, referring to figure 4a, 4b, of the present invention is disclosed a second interlock mechanism, wherein the Reverse (R) gear is locked.
1. engages the range gear in high and speed gears at 3rd and 4th position and locks the reverse gears; or
2. engages the range gear in high and engage the reverse gears and locks the speed gears at the 3rdand 4th position or
3. engages the reverse gears and speed gears at the 3rd or 4th position and locks the range gears in high position.

In the preferred embodiment of the present invention a dual interlocking system for locks the speed gears in the 3rd and 4th position at high ranges in the reverse direction

In the preferred embodiment of the present invention the said gear shifting levers comprising of: first gear shifting levers positioned at the right side of tractor to engage the said speed gears for speeds 1-2-3-4 ; a second gear shifting lever positioned on the left of the tractor to engage the range gears of high and low; a third gear shift lever positioned on the instrument panel of the tractor to engage the forward (F) and reverse gears (R)

In the preferred embodiment of the present invention the dual interlocking system includes gear shifting rails comprises : a first rail (101) having 1st and 2nd gear position; a second rail (102) having 3rd and 4th positions; a third rail (103) having and forward and reverse direction, fourth rail (104) having range gears of high and low wherein the upon operation, the shift lever selects the gear and the rail moves a fork that’s attached to gear or sleeve.

In the preferred embodiment of the present invention ball interlocks and pin interlock (107) assembled in the gear shifting rails (101, 102, 103, 104) for sensing the rail movements corresponding to the speed gears and lock the forward and reverse rail (103) during reverse gear engagement. Upon engagement of the ball interlock (105b and 105c), pin interlock is locked between the said ball interlocks (105) locking the gears in high ranges in the reverse direction

In the preferred embodiment of the present invention dual interlocking system locks reverse speed more than 20 Kmph.

In a preferred embodiment of the present invention of the dual interlocking system , the ball interlock (105a) is assembled within the ball retainer (106) between third and fourth positions to avoid double engagement of the gears. (figure 1b, 1c)
The present invention also provides a method of operation of the dual interlocking system for shuttle transmission in agricultural tractors, the said method comprising the steps of:
i) operator moving the gear shift lever to select the gear
ii) movement of the rail corresponding to the fork attached to gear or sleeve.
iii) assembling the ball interlocks (105a, 105b, 105c) in between the rails (101, 102, 103, 104) in a predefined position upon the shifting of lever
iv) Pin interlock (107) operatively positioned in a rail (103), to assemble pin interlock (107) in rail (103), a slot machining provided in rail (103).
v) ensure working of first interlock mechanism groove (108) provided in first rail (101) and a second rail (102).
In exemplary embodiments the shape of the pin interlock and the slot is oval.
In an embodiment of the present invention as illustrated in fig 3(a) and 3(b), in the first interlock mechanism , during the engagement of the first rail (101) in the 1st or 2nd gear position , ball interlock (105a) seats on groves of second rail (102) in 3rd and 4th gear position locked in the said second rail. Similarly, during the engagement of the second rail in the 3rd or 4th gear position, ball interlock (105a) moves and seats on groves of first rail in the 1st and 2nd gear position locking the said first rail.

In an embodiment of the present invention, as illustrated in fig 4(a) and fig 4(b) during the second interlock mechanism, movement of ball interlock (105b and 105c) towards the said third rail (103) having forward and reverse ranges, locks the pin interlock (107) in the reverse position between the ball interlocks (105a and 105c). Thus, high gear, third and fourth gear are engaged and reverse gear is locked. Ref is drawn to figure 4(a) shift rail 103 moved to position 4 as provided in the drawing and ball 105b moves towards shift rail F/R (103). Fourth rail H-L (104) moves to position H i..e towards left and ball 105c moves towards the rail F-R (103). After ball 105b and 105c movements, pin interlock (107) is locked between the 2 balls and doesn’t allow the rail F-R (103) on reverse (R) position. Since pin interlock positioned after ball and groove (110) machining on Rail F/R (103) is allowing the movement of gear shifting FWD position FWD.

In an embodiment of the present invention, as illustrated in fig 5(a) and 5(b) during the second interlock mechanism , movement of the said fourth rail for H-L (104) in the high range position or H position and moves of ball interlock (5c) towards the third rail in the forward and reverse ranges (103). Further, movement of the said third rail to the reverse range position moves the pin interlock (107) and pushing the ball interlock (105b) to the second rail (102) grooves (109). It further, results in the seating of ball interlock (105b), and locking the second rail (102) having 3rd and 4th positions.

In an embodiment of the present invention as illustrated in fig 6(a) and 6(b) during the second interlock mechanism, involves engagement of the second rail (102) to fourth position and moving ball interlock (105b) towards the third rail (103) in the forward and reverse ranges. Further the said third rail (103) moves in the reverse position thereby moving the pin interlock (107) to push the ball interlock (105c) into rail (104) groove (111). After movement of ball 105b, pin interlock (107) and ball (105c) is locked in rail (104) groove (111) and doesn’t allow the rail H-L (104) on High position. Since groove (111) portion made as a lengthy rail H-L (104) is allowing the movement of gear shifting L position.
For illustration,
Example 1:
Interlock mechanism 1 – 1st / 2nd gear engagement – 3rd /4th gear in locking

In a specific example of the invention during the working of first interlock mechanism in order to avoid the double engagement of the four speed gears ball interlock(105a) is assembled between Rail1-2 and Rail 3-4 and this interlocking ball is assembled in the ball retainer (6). In this arrangement to select the Gear-1, Rail 1-2 move from neutral to 1st gear position. During movement of Rail 1-2, ball interlock (105a) moves and seats on Rail 3-4 groove. Hence movement of Rail 3-4 is locked and gear 3-4 cannot be shifted. Similarly during Rail 3-4 movement, Ball 105a moves and seats on Rail 1-2 grooves and this will not allow the gear shifting of Rail1-2, thus locking Rail 1-2. Conventionally, other gears shift levers such as forward-reverse and high-low are independent and no locking mechanism is available.

Example 2
Inter lock mechanism -2
In 8x8 shuttle transmission, there are 4 speed gears with high(H) and low(L) range in forward(F) & reverse(R) selection which denote as FL1, FL2,FL3, FL4, FH1, FH2, FH3, FH4 and RL1, RL2, RL3, RL4, RH1, RH2, RH3, RH4. During RH3 & RH4 gear selection, the tractor speed found 26.9 KMPH & 36.8 KMPH. These speed are more the 20KMPH IS12207-2019 standard requirement where these two speeds are not used in any of application range, which is intentionally locked by the dual interlocking system of the present invention
In a specific example of the second interlock mechanism in order to lock the reverse speed more than 20 KMPH, RH3 and RH4 found more than 20 KMPH. Thus two interlocking balls are assembled , Ball 105b assembled between Rail 3-4 & Rail F-R and Ball 105c assemble. In addition to interlocking balls, interlocking pin assembled (fig 1(a) and (b)) in Rail F/R hole for sense the Rail3-4 & Rail H-L movement through steel balls and lock the Rail F/R during reverse gear engagement. The groove machining provided in Rail F/R and Rail H-L, For allow the Rail F/R movement in Forward gear selection and also allow the Rail H-L movement in Low gear selection when 3rd gear or 4th gear engaged. (i. e – FH3 & FH4). In this mechanism, protected for locking of any condition high reverse of 3rd - 4th gears cannot be engaged. i,e RH3 or R3H or HR3 or H3R or 3HR or 3RH and same for 4th gears also.
Tractor speed details – 8X8 Gear box
Rated engine RPM 2200
Gear FWD REV
LOW 1 2.48 2.92
2 3.72 4.38
3 5.40 6.35
4 7.67 9.02
HIGH 1 10.16 11.94
2 15.23 17.91
3 22.09
25.97
4 31.36
36.88

The two reverse speed in the third and fourth position is locked in high ranges, (i.e RH3 & RH4 gear selection is intentionally locked)
Example 2
Interlock mechanism 2: Condition 1 - High gear, 3rd /4th Gear engaged & Reverse gear in locking
In a specific example of the present invention during the working of the second interlock mechanism , in the third and fourth gear selection , Rail 3-4 is moved from neutral to position 3 or 4 . Thus, during Rail 3-4 movement, Ball 105b moved toward Rail F/R. Similarly, during high gear selection, Rail H-L moves from neutral to H position and ball 105c moved towards Rail F/R. Correspondingly, after the movement of 105b and 105c, pin interlock is locked between these said balls 105b and 105c and not able to allow the Rail H-R on R position, thereby locking the reverse gear .
In the above mentioned condition said pin interlock is assembled in Rail F/R hole portion and both sides of rail F/R steel ball occupied in Rail F/R slot, the movement of Rail F/R in reverse direction is thus locked (i.e. H3R / 3HR and H4R / 4HR).Also, since pin interlock positioned after ball and due to slot machining in Rail F/R, movement of Rail F/R in forward direction is possible. (i,e H3F / 3HF and H4F / 4HF) . Further, slot machining on Rail F/R, gear shifting position of the forward is possible.
Example 3
Interlock mechanism 2 : Condition 2 - High gear, Reverse engaged & 3 / 4 gears are in locking
In another specific example of the present invention during the working of the second interlock mechanism in the high gear selection, Rail H-L move from neutral to H position. During Rail H-L movement ball 105c move towards Rail F/R and pushes the pin interlock. Similarly, during reverse gear selection, Rail F/R moves from neutral to R position. Further, during Rail F/R movement pin interlock also moves along with Rail F/R and Pin interlock pushes the ball 105b, thereby the ball 105b seats on Rail 3-4 groove. After the seating of ball 105b on Rail 3-4 groove, movement Rail 3-4 is restricted. Hence shifting of third or fourth gear is not possible. (ie HR3 / RH3 and HR4 / RH4 not allowed).
Example 4

Condition-3: 3rd /4th Gear, Rev gear engaged & High gear in locking

In another specific example during the second interlock mechanism in the third or fourth gear selection, Rail 3-4 move from neutral to 3 or 4 position. During Rail 3-4 movement, Ball 105b move towards Rail F/R and pushes the pin interlock. Similarly during the reverse gear selection, Rail F/R moves from neutral to R position. During Rail F/R movement pin interlock also moves along with Rail F/R and pin interlock pushes the ball 105c and this ball 105c seats on Rail H-L slot groove. After the seating of ball 105c on Rail H-L groove, gear shifting of the high range is not allowed i.e movement of Rail H-L in H direction is not allowed. (3RH / 4RH and R3H / R4H is locked). In this condition due to slot machining in Rail H-L, thus movement of Rail H-L in L direction is possible. Therefore, the gear shifting in the Gear shifting in the low ranges such as 3RL / 4RL and R3L / R4L is possible .

It will be apparent to a person skilled in the art that the above description is for illustrative purposes only and should not be considered as limiting. Various modifications, additions, alterations, and improvements without deviating from the spirit and the scope of the invention may be made by a person skilled in the art.