Transmission coordinating system with anti-stall means for vehicles having a plurality of engines

Claim 2

In a vehicle having a first engine driving a first ground engaging member through a master transmission and a second engine driving a second ground engaging member through a slave transmission wherein each of said transmissions may be shifted to provide a plurality of drive ranges, a system for coordinating said transmissions comprising: signal generating means linked to said master transmission for producing signals indicative of the drive range existing in said master transmission, a remote control unit coupled to said slave transmission and having means for shifting said slave transmission in response to said signals from said signal generating means to maintain said slave transmission at a drive range corresponding to that of said master transmission, and anti-stall means for downshifting said slave transmission to a predetermined drive range when the ground speed of said vehicle is below a predetermined value and the signal received from said signal generating means indicates a drive range higher than said predetermined drive range.

Claim 3

The combination of claim 1 wherein said slave transmission includes means providing a hydrodynamic power path in at least one drive range and providing a wholly mechanical power path at higher drive ranges wherein said predetermined drive range is said one which has a hydrodynamic power path.

Claim 4

The combination of claim 1 wherein said anti-stall means comprises switch means having a first state at which said signals from said signal generating means are transmitted to said remote control unit and having a second state at which said transmitting of said signals thereto is stopped and a signal indicative of said predetermined drive range is transmitted thereto, and ground speed sensing means for switching said switch means to said second state when ground speed decreases below said predetermined value while said signal generating means is producing a signal indicative of a higher speed range than said predetermined speed range.

Claim 5

The combination of claim 3 further comprising means for switching said switch means from said second state to said first state in response to an increase of ground speed to a value which is greater than said predetermined value which switches said switch means from said first state to said second state in response to decreasing ground speed.

Claim 6

The combination defined in claim 3 wherein said ground speed sensing device is a fluid pump driven through said slave transmission and wherein said switch means is a fluid pressure operated switch responsive to output pressure from said pump.

Claim 7

The combination defined in claim 5 further comprising a valve connected between said pump and said pressure operated switch and having means for responding to a rise of output pressure from said pump to a predetermined value by abruptly applying a still greater pressure to said switch and having means for abruptly decreasing the pressure applied to said switch when said applied pressure drops to said predetermined value whereby said pressure switch is switched from said second state to said first state in response to an increase of ground speed to a particular value and is restored to said second state in response to a decrease of ground speed to a lesser value.

Claim 8

The combination defined in claim 6 wherein said valve comprises a valve body having a bore therein and having an inlet communicating with said bore for receiving said output pressure of said pump and having an outlet communicated with said pressne switch and having a drain passage means, a valve spool slidable within said bore and having a fluid chamber within said spool and a passage for communicating said valve body inlet with said fluid chamber and having a first flow orifice communicating said fluid chamber with said pressure switch inlet and having a second flow orifice communicating said chamber with said drain passage and having a first edge which vents said pressure switch inlet to said drain passage means at a first position of said valve and which blocks said pressure switch inlet from said drain passage means when said spool is shifted away from said first position thereof by a predetermined amount and having a second edge which vents said fluid chamber to said drain passage when said spool is shifted away from said first position by a still greater amount, and resilient means exerting a force on said spool in a direction urging said spool towards said first position thereof.

Claim 9

The combination of claim 1 wherein said master transmission has means for manually establishing a selected one of a plurality of lower drive ranges therein and has self controlled shifting means for establishing any of a plurality of higher drive ranges therein, further comprising mens for inactivating said anti-stall means in response to manual shifting of said master transmission into one of said lower drive ranges.

Claim 10

The combination of claim 8 wherein the drive range of said master transmission is established by a shift control means having an element which moves to a distinct position for each drive range in said master transmission, and wherein said remote control unit has a plurality of signal input means which may be individually energized to establish specific drive ranges in said slave transmission, said signal generating means comprising: a first switch having means for connecting a first input terminal to a different one of a first plurality of output terminals in response to shifting of said element of said shift control means to different ones of said positions thereof that correspond to different ones of said plurality of lower drive ranges, A second switch having means for connecting a second input terminal to a different one of a second plurality of output terminals in response to shifting of said element of said shift control means to different ones of said positions thereof that correspond to different ones of said plurality of higher drive ranges, conductor means connecting individual of said first and second pluralities of output terminals with corresponding individual ones of said signal input means of said remote control unit, means energizing said input terminal of said first switch, and means for energizing said input terminal of said second switch only when said element of said shift control is at a position corresponding to one of said higher drive ranges and said ground speed of said vehicle is above said predetermined value.

Claim 11

The combination of claim 9 wherein said anti-stall means comprises a third switch having a common terminal receiving energization through said first switch only when said element of said shift control means is at a position corresponding to one of said higher drive ranges and having a first output terMinal connected to said input terminal of said second switch and having a second output terminal connected to a predetermined one of said signal input means of said remote control unit, said third switch having an unactuated condition at which said common terminal is connected to said second output terminal and is disconnected from said first output terminal and having an actuated position at which said common terminal is disconnected from said second output terminal and is connected to said first output terminal, and means for actuating said third switch when said ground speed of said vehicle exceeds a predetermined amount.