Electrical automatic transmission control system with two two-way electrically controlled valves and hydraulic switching valve

Claim 2

An electrically activated transmission control system, for a vehicle automatic transmission comprising a gear transmission mechanism which comprises a plurality of hydraulic fluid pressure activated friction engaging mechanisms and which provides a first forward speed stage, a second forward speed stage which is higher geared than said first forward speed stage, a third forward speed stage which is higher geared than said first and second forward speed stages, and a fourth forward speed-stage which is higher geared than said first, second, and third forward speed stages, according to selective supply of hydraulic fluid pressure to said hydraulic fluid pressure activated friction engaging mechanisms, comprising: (a) a first electrically activated switching valve system, which is switched between a first state and a second state according to selective supply of activating electrical energy thereto, and which selectively controls supply of activating hydraulic fluid pressure to at least some of said hydraulic fluid pressure activated friction engaging mechanisms, according to its switched state; its said first state so controlling supply of activating hydraulic fluid pressure to said hydraulic fluid pressure activated friction engaging mechanisms as to cause said gear transmission mechanism to provide either one of a certain two of said four forward speed stages, and its said second state so controlling supply of activating hydraulic fluid pressure to said hydraulic fluid pressure activated friction engaging mechanisms as to cause said gear transmission mechanism to provide either one of the other two of said four forward speed stages; and (b) a second electrically activated switching valve system, which is switched between a first state and a second state according to selective supply of activating electrical energy thereto, and which selectively controls supply of activating hydraulic fluid pressure to at least some of said hydraulic fluid pressure activated friction engaging mechanisms, according to its switched state; its said first state so controlling supply of activating hydraulic fluid pressure to said hydraulic fluid pressure activated friction engaging mechanisms as to cause said gear transmission mechanism to provide either a one of said certain two of said forward speed stages, or a one of said other two of said four forward speed stages, and its said second state so controlling supply of activating hydraulic fluid pressure to said hydraulic fluid pressure activated friction engaging mechanisms as to cause said gear transmission mechanism to provide either the other one of said certain two of said four forward speed stages, or the other one of said other two of said four forward speed stages; characterized by further comprising: (c) a hydraulic fluid pressure activated switching valve, which is switched between a first state and a second state according to a first hydraulic fluid pressure which is controlled in relation to the switching operation of said first electrically activated switching valve system and also according to a second hydraulic fluid pressure which is controlled in relation to the switching operation of said second electrically activated switching valve system; (d) the switching of said hydraulic fluid pressure activated switching valve between its said first state and its said second state controlling supply of hydraulic fluid pressure to at least some of said hydraulic fluid pressure activated friction engaging mechanisms, so as to cause said gear transmission mechanism selectively to provide either a first particular one of said four forward speed stages, or another particular one of said four forward speed stages, according as to whether said hydraulic fluid pressure activated switching valve is in its said first state or is in its said second state.

Claim 3

A transmission control system according to claim 1, characterized in that said first particular one of said four forward speed stages and said another particular one of said four forward speed stages are adjacent speed stages.

Claim 4

A transmission control system according to claim 2, characterized in that said first particular one of said four forward speed stages is said third forward speed stage, and said another particular one of said four forward speed stages is said fourth forward speed stage.

Claim 5

A transmission control system according to claim 3, characterized in that said certain two of said four forward speed stages are said first forward speed stage and said second forward speed stage, said other two of said four forward speed stages are said third forward speed stage and said -fourth forward speed stage, said one of said certain two of said four forward speed stages is said second forward speed stage, and said one of said other two of said four forward speed stages is said third forward speed stage; said other one of said certain two of said four forward speed stages being said first forward speed stage, and said other one of said other two of said four forward speed stages being said fourth forward speed stage.

Claim 6

A transmission control system according to claim 4, characterized in that said third forward speed stage is a directly connected speed stage, and said fourth forward speed stage is an overdrive speed stage.

Claim 7

An electrically activated transmission control system, for a vehicle automatic transmission comprising a gear transmission mechanism which comprises a plurality of hydraulic fluid pressure activated friction engaging mechanisms and which provides a first forward speed stage, a second forward speed stage which is higher geared than said first forward speed stage, a third forward speed stage which is a directly connected speed stage and which is higher geared than said first and second forward speed stages, and a fourth forward speed stage which is an overdrive speed stage and which is higher geared than said first, second, and third forward speed stages, according to selective supply of hydraulic fluid pressure to said hydraulic fluid pressure activated friction engaging mechanisms, characterized by comprising: (a) a first electrically activated switching valve system, which is switched between a first state and a second state according to selective supply of activating electrical energy thereto, and which selectively controls supply of activating hydraulic fluid pressure to at least some of said hydraulic fluid pressure activated friction engaging mechanisms, according to its switched state; its said first state so controlling supply of activating hydraulic fluid pressure to said hydraulic fluid pressure activated friction engaging mechanisms as to cause said gear transmission mechanism to provide either said first forward speed stage or said second forward speed stage, and its said second state so controlling supply of activating hydraulic fluid pressure to said hydraulic fluid pressure activated friction engaging mechanisms as to cause said gear transmission mechanism to provide either said directly connected third forward speed stage or said overdrive fourth forward speed stage; (b) a second electrically activated switching valve system, which is switched between a first state and a second state according to selective supply of activating electrical energy thereto, and which selectively controls supply of activating hydraulic fluid pressure to at least some of said hydraulic fluid pressure activated friction engaging mechanisms, according to its switched state; its said first state so controlling supply of activating hydraulic fluid pressure to said hydraulic fluid pressure activated friction engaging mechanisms as to cause said gear transmission mechanism to provide either said second forward speed stage or said directly connected third forward speed stage, and its said second state so controlling supply of activating hydraulic fluid pressure to said hydraulic fluid pressure activated friction engaging mechanisms as to cause said gear transmission mechanism to provide either said first forward speed stage or said overdrive fourth forward speed stage; and (c) a hydraulic fluid pressure activated switching valve, which is switched between a first state and a second state according to a first hydraulic fluid pressure which is controlled in relation to the switching operation of said first electrically activated switching valve system and also according to a second hydraulic fluid pressure which is controlled in relation to the switching operation of said second electrically activated switching valve system; (d) the switching of said hydraulic fluid pressure activated switching valve between its said first state and its said second state controlling supply of hydraulic fluid pressure to at least some of said hydraulic fluid pressure activated friction engaging mechanisms, so as to cause said gear transmission mechanism selectively to provide either said directly connected third forward speed stage, or said overdrive fourth forward speed stage, according as to whether said hydraulic fluid pressure activated switching valve is respectively in its said first state or is in its said second state.

Claim 8

An electrically activated transmission control system, for a vehicle automatic transmission comprising a gear transmission mechanism which comprises a plurality of hydraulic fluid pressure activated friction engaging mechanisms and which provides a first forward speed stage, a second forward speed stage which is higher geared than said first forward speed stage, a third forward speed stage which is a directly connected speed stage and which is higher geared than said first and second forward speed stages, and a fourth forward speed stage which is an overdrive speed stage and which is higher geared than said first, second, and third forward speed stages, according to selective supply of hydraulic fluid pressure to said hydraulic fluid pressure activated friction engaging mechanisms, characterized by comprising: (a) a first electrically activated switching valve system, which is switched between a first state and a second state according to selective supply of activating electrical energy thereto, and which selectively controls supply of activating hydraulic fluid pressure to at least some of said hydraulic fluid pressure activated friction engaging mechanisms, according to its switched state; its said first state so controlling supply of activating hydraulic fluid pressure to said hydraulic fluid pressure activated friction engaging mechanisms as to cause said gear transmission mechanism to provide either said first forward speed stage or said second forward speed stage, and its said second state so controlling supply of activating hydraulic fluid pressure to said hydraulic fluid pressure activated friction engaging mechanisms as to cause said gear transmission mechanism to provide either said directly connected third forward speed stage or said overdrive fourth forward speed stage; (b) a second electrically activated switching valve system, which is switched between a first state and a second state according to selective supply of activating electrical energy thereto, and which selectively controls supply of activating hydraulic fluid pressure to at least some of said hydraulic fluid pressure activated friction engaging mechanisms, according to its switched state; its said first state so controlling supply of activating hydraulic fluid pressure to said hydraulic fluid pressure activated friction engaging mechanisms as to cause said gear transmission mechanism to provide either said second forward speed stage or said directly connected third forward speed stage, and its said second state so controlling supply of activating hydraulic fluid pressure to said hydraulic fluid pressure activated friction engaging mechanisms as to cause said gear transmission mechanism to provide either said first forward speed stage or said overdrive fourth forward speed stage; and (c) a hydraulic fluid pressure activated switching valve, which is switched between a first state and a second state according to a first hydraulic fluid pressure which is controlled in relation to the switching operation of said first electrically activated switching valve system and also according to a second hydraulic fluid pressure which is controlled in relation to the switching operation of said second electrically activated switching valve system; (d) the switching of said hydraulic fluid pressure activated switching valve between its said first state and its said second state controlling supply of hydraulic fluid pressure to at least some of said hydraulic fluid pressure activated friction engaging mechanisms, so as to cause said gear transmission mechanism selectively to provide either said directly connected third forward speed stage, or said overdrive fourth forward speed stage, according as to whether said hydraulic fluid pressure activated switching valve is respectively in its said first state or is in its said second state.

Claim 9

A transmission control system according to any one of claims 4, 5, or 6, characterized by further comprising a manual range selection valve which can be manually shifted to any one of a set of positions indicating "D" range, "3" range, and "L" range, and which produces various combinations of output hydraulic fluid pressures according to its shifted position, including a first output hydraulic fluid pressure which is output from said manual range selection valve when said manual range selection valve is shifted to either its said position indicating "3" range or its said position indicating "L" range, and which, when so output, is supplied to said hydraulic fluid pressure activated switching valve, so as positively to overridingly switch said hydraulic fluid pressure activated switching valve to its said first state, irrespective of any other hydraulic fluid pressures supplied to said hydraulic fluid pressure activated switching valve.

Claim 10

A transmission control system according to claim 7, said manual range shifting valve being additionally shiftable to a position indicating "R" range, characterized in that: (e) said first electrically activated switching valve system comprises: (el) a first solenoid valve which when and only when not energized provides a first transferred hydraulic fluid pressure supply of a second output hydraulic fluid pressure which is output from said manual range selection valve when and only when said manual range selection valve is shifted to either its said position indicating "D" range, to its said position indicating "3" range, or to its said position indicating "L" range; and (e2) a first switching valve which is switched between a first state and a second state according to the selective supply of hydraulic fluid pressures including said first transferred hydraulic fluid pressure thereto, and which is biased towards its said second state by said first transferred hydraulic fluid pressure; (f) said second electrically activated switching valve system comprises: (fl) a second solenoid valve which when and only when not energized provides a second transferred hydraulic fluid pressure supply of said second output hydraulic fluid pressure; and (f2) a second switching valve which is switched between a first state and a second state according to the selective supply of hydraulic fluid pressures including said second transferred hydraulic fluid pressure thereto, and which is biased towards its said second state by said second transferred hydraulic fluid pressure; (g) said first state and said second state of said first electrically activated switching valve system are respectively the electrically energized state and the electrically non energized state of said first solenoid valve, and said first state and said second state of said second electrically activated switching valve system are respectively the electrically energized state and the electrically non energized state of said second solenoid valve; (h) a third output hydraulic fluid pressure which is output from said manual range selection valve when and only when said manual range selection valve is shifted to its said position indicating "L" range is supplied to said first electrically activated switching valve system and when present positively overridingly switches said first switching valve to its said first state, irrespective of any other hydraulic fluid pressures being supplied to said first switching valve; (i) a fifth hydraulic fluid pressure, switched by said first switching valve both from said second output hydraulic fluid pressure and from a fourth output hydraulic fluid pressure which is output from said manual range selection valve when and only when said manual range selection valve is shifted to its said position indicating "R" range, said fifth hydraulic fluid pressure being present when and only when either said manual switching valve is shifted to its said position indicating "R" range and in addition said first switching valve is in its said first state, or said manual switching valve is shifted either to its said position indicating "D" range, to its said position indicating "3" range, or to its said position indicating "L" range and in addition said first switching valve is in its said second state, is supplied to said second electrically activated switching valve system and when present positively overridingly switches said second switching valve to its said first state, irrespective of any other hydraulic fluid pressures being supplied to said second switching valve; (j) said first switching valve switches a supply of said second output hydraulic fluid pressure to said hydraulic fluid pressure activated switching valve when said first switching valve is in its said first state, said supply of hydraulic fluid pressure positively overridingly switching said hydraulic fluid pressure activated switching valve to its said first state, irrespective of any other hydraulic fluid pressures being supplied to said second switching valve; and (k) no other fluid pressures activate said first and second switching valves and said hydraulic fluid pressure activated switching valve to switch them.

Claim 11

An electrically activated transmission control system, for a vehicle automatic transmission comprising a gear transmission mechanism which comprises a plurality of hydraulic fluid pressure activated friction engaging mechanisms and which provides a reverse driving stage, a first forward speed stage, a second forward speed stage which is higher geared than said first forward speed stage, a third forward speed stage which is a directly connected speed stage and which is higher geared than said first and second forward speed stages, and a fourth forward speed stage which is an overdrive speed stage and which is higher geared than said first, second, and third forward speed stages, according to selective supply of activating hydraulic fluid pressure to said hydraulic fluid pressure activated friction engaging mechanisms, said transmission also comprising a manual range selection valve which can be manually shifted to any one of a set of positions indicating "D" range, "3" range, "L" range, and "R" range, and which produces various combinations of output hydraulic fluid pressures according to its shifted position, including: a first output hydraulic fluid pressure which is output from said manual range selection valve when and only when said manual range selection valve is shifted either to its said position indicating "3" range or to its said position indicating "L" range; a second output hydraulic fluid pressure which is output from said manual range selection valve when and only when said manual range selection valve is shifted either to its said position indicating "D" range, to its said position indicating "3" range, or to its said position indicating "L" range; a third output hydraulic fluid pressure which is output from said manual range selection valve when and only when said manual range selection valve is shifted to its said position indicating "L" range; and a fourth output hydraulic fluid pressure which is output from said manual range selection valve when and only when said manual range selection valve is shifted to its said position indicating "R" range, characterized by comprising: (a) a first electrically activated switching valve system, comprising: (al) a first solenoid valve which when and only when not electrically energized provides a first transferred hydraulic fluid pressure supply. of said second output hydraulic fluid pressure; and (a2) a first switching valve which is switched between a first state and a second state, being biased towards its said second state by said first transferred hydraulic fluid pressure, and being biased towards its said first state by supply of said third output hydraulic fluid pressure when said third output hydraulic fluid pressure is output from said manual range selection valve; said first switching valve not being switchingly biased by any other hydraulic fluid pressures; said first switching valve, when not biased by any hydraulic fluid pressures, being in its said first state; said first switching valve, when biased both towards its said first state and also towards its said second state, being in its said first state; and said first switching valve selectively controlling supply of activating hydraulic fluid pressure to at least some of said hydraulic fluid pressure activated friction engaging mechanisms, according to its switched state; (b) a second electrically activated switching valve system, comprising: (bl) a second solenoid valve which when and only when not electrically energized provides a second transferred hydraulic fluid pressure supply of said second output hydraulic fluid pressure; and (b2) a second switching valve which is switched between a first state and a second state, being biased towards its said second state by said second transferred hydraulic fluid pressure, and being biased towards its said first state by a fifth hydraulic fluid pressure switched by said first switching valve either from said second output hydraulic fluid pressure when said second output hydraulic fluid pressure is output from said manual range selection valve or from said fourth output hydraulic fluid pressure when said fourth output hydraulic fluid pressure is output from said manual range selection valve, said fifth hydraulic fluid pressure being present when and only when either said fourth output hydraulic fluid pressure is present and in addition said first switching valve is in its said first state, or said second output hydraulic fluid pressure is present and in addition said first switching valve is in its said second state; said second switching valve not being switchingly biased by any other hydraulic fluid pressures; said second switching valve, when not biased by any hydraulic fluid pressures, being in its said first state; said second switching valve, when biased both towards its said first state and also towards its said second state, being in its said first state; and said second switching valve selectively controlling supply of activating hydraulic fluid pressure to at least some of said hydraulic fluid pressure activated friction engaging mechanisms, according to its switched state; and (c) a hydraulic fluid pressure activated switching valve which is switched between a first state and a second state, being biased towards its said second state by said second transferred hydraulic fluid pressure, and being biased towards its said first state by said first output hydraulic fluid pressure and also by a supply of said second output hydraulic fluid pressure which is switched thereto by said first switching valve when and only when said second output hydraulic fluid pressure is output by said manual range selection valve and also said first switching valve is in its said first state; said hydraulic fluid pressure activated switching valve not being switchingly biased by any other hydraulic fluid pressures; said hydraulic fluid pressure activated switching valve, when not biased by any hydraulic fluid pressures, being in its said first state; said hydraulic fluid pressure activated switching valve, when biased both towards its said first state and also towards its said second state, being in its said first state; and said hydraulic fluid pressure activated switching valve selectively controlling supply of activating hydraulic fluid pressure to at least some of said hydraulic fluid pressure activated friction engaging mechanisms, according to its switched state; (d) with said manual range selection valve shifted to its said position indicating "D" range: the combination of said first and second solenoid valves being respectively in the energized and in the not energized states, said first switching valve being in its said first state, said second switching valve being in its said second state, and said hydraulic fluid pressure, activated switching valve being in its said first state providing such a combination of activating hydraulic fluid pressures to said hydraulic fluid pressure activated friction engaging mechanisms of said gear transmission mechanism as to cause said gear transmission mechanism to provide its first speed stage; the combination of said first and second solenoid valves being both in their energized states, said first switching valve being in its said first state, said second switching valve being in its said first state, and said hydraulic fluid pressure activated switching valve being in its said first state providing such a combination of activating hydraulic fluid pressures to said hydraulic fluid pressure activated friction engaging mechanisms of said gear transmission mechanism as to cause said gear transmission mechanism to provide its second speed stage; the combination of said first and second solenoid valves being respectively in the not energized and in the energized states, said first switching valve being in its said second state, said second switching valve being in its said first state, and said hydraulic fluid pressure activated switching valve being in its said first state providing such a combination of activating hydraulic fluid pressures to said hydraulic fluid pressure activated friction engaging mechanisms of said gear transmission mechanism as to cause said gear transmission mechanism to provide its directly connected third speed stage; and the combination of said first and second solenoid valves being both in their not energized states, said first switching valve being in its said second state, said second switching valve being in its said first state, and said hydraulic fluid pressure activated switching valve being in its said second state providing such a combination of activating hydraulic fluid pressures to said hydraulic fluid pressure activated friction engaging mechanisms of said gear transmission mechanism as to cause said gear transmission mechanism to provide its overdrive fourth speed stage.

Claim 12

An electrically activated transmission control system, for a vehicle automatic transmission comprising a gear transmission mechanism which comprises a plurality of hydraulic fluid pressure activated friction engaging mechanisms and which provides a reverse driving stage, a first forward speed stage, a second forward speed stage which is higher geared than said first forward speed stage, a third forward speed stage which is a directly connected speed stage and which is higher geared than said first and second forward speed stages, and a fourth forward speed stage which is an overdrive speed stage and which is higher geared than said first, second, and third forward speed stages, according to selective supply of activating hydraulic fluid pressure to said hydraulic fluid pressure activated friction engaging mechanisms, said transmission also comprising a manual range selection valve which can be manually shifted to any one of a set of positions indicating "D" range, "3" range, "L" range, and "R" range, and which produces various combinations of output hydraulic fluid pressures according to its shifted position, including: a first output hydraulic fluid pressure which is output from said manual range selection valve when and only when said manual range selection valve is shifted either to its said position indicating "3" range or to its said position indicating "L" range; a second output hydraulic fluid pressure which is output from said manual range selection valve when and only when said manual range selection valve is shifted either to its said position indicating "D" range, to its said position indicating "3" range, or to its said position indicating "L" range; a third output hydraulic fluid pressure which is output from said manual range selection valve when and only when said manual range selection valve is shifted to its said position indicating "L" range; and a fourth output hydraulic fluid pressure which is output from said manual range selection valve when and only when said manual range selection valve is shifted to its said position indicating "R" range, characterized by comprising: (a) a first electrically activated switching valve system, comprising: (al) a first solenoid valve which when and only when not electrically energized provides a first transferred hydraulic fluid pressure supply. of said second output hydraulic fluid pressure; and (a2) a first switching valve which is switched between a first state and a second state, being biased towards its said second state by said first transferred hydraulic fluid pressure, and being biased towards its said first state by supply of said third output hydraulic fluid pressure when said third output hydraulic fluid pressure is output from said manual range selection valve; said first switching valve not being switchingly biased by any other hydraulic fluid pressures; said first switching valve, when not biased by any hydraulic fluid pressures, being in its said first state; said first switching valve, when biased both towards its said first state and also towards its said second state, being in its said first state; and said first switching valve selectively controlling supply of activating hydraulic fluid pressure to at least some of said hydraulic fluid pressure activated friction engaging mechanisms, according to its switched state; (b) a second electrically activated switching valve system, comprising: (bl) a second solenoid valve which when and only when not electrically energized provides a second transferred hydraulic fluid pressure supply of said second output hydraulic fluid pressure; and (b2) a second switching valve which is switched between a first state and a second state, being biased towards its said second state by said second transferred hydraulic fluid pressure, and being biased towards its said first state by a fifth hydraulic fluid pressure switched by said first switching valve either from said second output hydraulic fluid pressure when said second output hydraulic fluid pressure is output from said manual range selection valve or from said fourth output hydraulic fluid pressure when said fourth output hydraulic fluid pressure is output from said manual range selection valve, said fifth hydraulic fluid pressure being present when and only when either said fourth output hydraulic fluid pressure is present and in addition said first switching valve is in its said first state, or said second output hydraulic fluid pressure is present and in addition said first switching valve is in its said second state; said second switching valve not being switchingly biased by any other hydraulic fluid pressures; said second switching valve, when not biased by any hydraulic fluid pressures, being in its said first state; said second switching valve, when biased both towards its said first state and also towards its said second state, being in its said first state; and said second switching valve selectively controlling supply of activating hydraulic fluid pressure to at least some of said hydraulic fluid pressure activated friction engaging mechanisms, according to its switched state; and (c) a hydraulic fluid pressure activated switching valve which is switched between a first state and a second state, being biased towards its said second state by said second transferred hydraulic fluid pressure, and being biased towards its said first state by said first output hydraulic fluid pressure and also by a supply of said second output hydraulic fluid pressure which is switched thereto by said first switching valve when and only when said second output hydraulic fluid pressure is output by said manual range selection valve and also said first switching valve is in its said first state; said hydraulic fluid pressure activated switching valve not being switchingly biased by any other hydraulic fluid pressures; said hydraulic fluid pressure activated switching valve, when not biased by any hydraulic fluid pressures, being in its said first state; said hydraulic fluid pressure activated switching valve, when biased both towards its said first state and also towards its said second state, being in its said first state; and said hydraulic fluid pressure activated switching valve selectively controlling supply of activating hydraulic fluid pressure to at least some of said hydraulic fluid pressure activated friction engaging mechanisms, according to its switched state; (d) with said manual range selection valve shifted to its said position indicating "D" range: the combination of said first and second solenoid valves being respectively in the energized and in the not energized states, said first switching valve being in its said first state, said second switching valve being in its said second state, and said hydraulic fluid pressure, activated switching valve being in its said first state providing such a combination of activating hydraulic fluid pressures to said hydraulic fluid pressure activated friction engaging mechanisms of said gear transmission mechanism as to cause said gear transmission mechanism to provide its first speed stage; the combination of said first and second solenoid valves being both in their energized states, said first switching valve being in its said first state, said second switching valve being in its said first state, and said hydraulic fluid pressure activated switching valve being in its said first state providing such a combination of activating hydraulic fluid pressures to said hydraulic fluid pressure activated friction engaging mechanisms of said gear transmission mechanism as to cause said gear transmission mechanism to provide its second speed stage; the combination of said first and second solenoid valves being respectively in the not energized and in the energized states, said first switching valve being in its said second state, said second switching valve being in its said first state, and said hydraulic fluid pressure activated switching valve being in its said first state providing such a combination of activating hydraulic fluid pressures to said hydraulic fluid pressure activated friction engaging mechanisms of said gear transmission mechanism as to cause said gear transmission mechanism to provide its directly connected third speed stage; and the combination of said first and second solenoid valves being both in their not energized states, said first switching valve being in its said second state, said second switching valve being in its said first state, and said hydraulic fluid pressure activated switching valve being in its said second state providing such a combination of activating hydraulic fluid pressures to said hydraulic fluid pressure activated friction engaging mechanisms of said gear transmission mechanism as to cause said gear transmission mechanism to provide its overdrive fourth speed stage.

Claim 13

A transmission control system according to claim 9, characterized in that: (e) with said manual range selection valve shifted to its said position indicating "D" range: the combination of said first and second solenoid valves being respectively in the energized and in the not energized states, said first switching valve being in its said first state, said second switching valve being in its said second state, and said hydraulic fluid pressure activated switching valve being in its said first state provides such a combination of activating hydraulic fluid pressures to said hydraulic fluid pressure activated friction engaging mechanisms of said gear transmission mechanism as to cause said gear transmission mechanism to provide its first speed stage with no engine braking being available; the combination of said first and second solenoid valves being both in their energized states, said first switching valve being in its said first state, said second switching valve being in its said first state, and said hydraulic fluid pressure activated switching valve being in its said first state provides such a combination of activating hydraulic fluid pressures to said hydraulic fluid pressure activated friction engaging mechanisms of said gear transmission mechanism as to cause said gear transmission mechanism to provide its second speed stage with no engine braking being available; and the combination of said first and second solenoid valves being respectively in the not energized and in the energized states, said first switching valve being in its said second state, said second switching valve being in its said first state, and said hydraulic fluid pressure activated switching valve being in its said first state provides such a combination of activating hydraulic fluid pressures to said hydraulic fluid pressure activated friction engaging mechanisms of said gear transmission mechanism as to cause said gear transmission mechanism to provide its third directly connected speed stage with engine braking being available; (f) with said manual range selection valve shifted to its said position indicating "3" range or to its said position indicating "L" range: the combination of said first and second solenoid valves being both in their energized states, said first switching valve being in its said first state, said second switching valve being in its said first state, and said hydraulic fluid pressure activated switching valve being in its said first state provides such a combination of activating hydraulic fluid pressures to said hydraulic fluid pressure activated friction engaging mechanisms of said gear transmission. mechanism as to cause said gear transmission mechanism to provide its second speed stage with engine braking being available; and (g) with said manual range selection valve shifted to its said position indicating "L" range: the combination of said first and second solenoid valves being respectively in the energized and in the not energized states, said first switching valve being in its said first state, said second switching valve being in its said second state, and said hydraulic fluid pressure activated switching valve being in its said first state provides such a combination of activating hydraulic fluid pressures to said hydraulic fluid pressure activated friction engaging mechanisms of said gear transmission mechanism as to cause said gear transmission mechanism to provide its _ first speed stage with engine braking being available.

Claim 14

A transmission control system according to claim 9, characterized in that: (h) the combination of said manual range selection valve being in its said position indicating "R" range, said first and second solenoid valves being both in their not energized states, said first switching valve being in its said first state, said second switching valve being in its said first state, and said hydraulic fluid pressure activated switching valve being in its said first state provides such a combination of activating hydraulic fluid pressures to said hydraulic fluid pressure activated friction engaging mechanisms of said gear transmission mechanism as to cause said gear transmission mechanism to provide its reverse driving stage; (i) the combination of said manual range selection valve being in its said position indicating "L" range, said first and second solenoid valves being both in their not energized states, said first switching valve being in its said first state, said second switching valve being in its said second state, and said hydraulic fluid pressure activated switching valve being in its said first state provides such a combination of activating hydraulic fluid pressures to said hydraulic fluid pressure activated friction engaging mechanisms of said gear transmission mechanism as to cause said gear transmission mechanism to provide its first speed stage; (j) the combination of said manual range selection valve being in its said position indicating "3" range, said first and second solenoid valves being both in their not energized states, said first switching valve being in its said second state, said second switching valve being in its said first state, and said hydraulic fluid pressure activated switching valve being in its said first state provides such a combination of activating hydraulic fluid pressures to said hydraulic fluid pressure activated friction engaging mechanisms of said gear transmission mechanism as to cause said gear transmission mechanism to provide its directly connected third speed stage; and (k) the combination of said manual range selection valve being in its said position indicating "D" range, said first and second solenoid valves being both in their not energized states, said first switching valve being in its said second state, said second switching valve being in its said first state, and said hydraulic fluid pressure activated switching valve being in its said second state provides such a combination of activating hydraulic fluid pressures to said hydraulic fluid pressure activated friction engaging mechanisms of said gear transmission mechanism as to cause said gear transmission mechanism to provide its overdrive fourth speed stage.