AUTOMATIC TRANSMISSION FOR VEHICLES

Abstract: An automatic transmission for a vehicle which automatically carries out transmission control in relation to the running of the vehicle. In addition to an operation lever (111, 112) such as a select lever, a hold switch (180) is provided for informing an automatic transmission controller (130) of the need for a hold operation to automatically hold the currently selected gear position (speed step) of the transmission (160). The hold operation is executed by the controller depending upon the operation of the hold switch. When the forward-reverse switching is effected after the hold switch is operated, furthermore, the transmission at the time of start is once switched (shifted) to the second speed step forcibly. As the desired speed step that is held is reached accompanying the rise of the vehicle speed, this speed step is automatically held as a result of the hold operation. Therefore, even vehicles for construction machinery such as wheel loaders are permitted to execute the operation efficiently and smoothly.

Description: The present invention relates generally to an automatic speed changing apparatus for a vehicle wherein speed changing in connection with movement of the vehicle is automatically controlled and more particularly to improvement of an automatic speed changing apparatus preferably employable for a transmission mounted on a tire type construction machine such as a wheel loader or the like vehicle. An automatic speed changing apparatus for a vehicle is disclosed in US-A-4 208 925. The known apparatus comprises a gear unit having one reverse speed, several forward speeds and a neutral position. A transmission control is provided for manual mode and automatic mode operation, depending on the position of a gear selector cane. If the cane is moved into a higher-gear position, the control will operate in automatic mode, with shifting occuring automatically, up or down, in a range from the minimum automatic gear to the maximum gear selected by the operator. Further, an operator-controlled hold switch is provided. By operation of this switch, the vehicle operator may inhibit shifting of the transmission and hold it in the gear that it is in. An automatic speed changing apparatus as disclosed in GB-A-2 055 999 allows the operator to preselect a different driving direction of the vehicle, whereafter the reversing process is carried out automatically. Once the operator has selected the desired driving direction, he needs not do anything more in the reversing process. When the retardation has been completed, the vehicle starts in the new direction via automatic control of the gear box. Fig. 1 schematically illustrates a technical concept representing a further conventional automatic speed changing apparatus which has been employed for a passenger car, a truck or the like vehicle. As shown in Fig. 1, the automatic speed changing apparatus is usually constructed such that the content of actuations of a select lever device 10 and an acceleration pedal 20 is inputted into a controller 30 comprising computors 31 and 32, and a rotational speed of an engine 40, a manner of turning on or off a clutch 50 and a manner of shifting gears in a transmission 60 are controlled to match the content of actuations of the select lever device 10 and the acceleration pedal 20. Here, the select lever device 10 is such that a select lever signal representative of the content corresponding to the actuation position is outputted in response to shifting actuation of a select lever 11 in the direction of an arrow mark F1 in the drawing. For example, when the select lever 11 is actuated to a "R (reverse)" position, a select lever signal representative of "rearward movement of a vehicle (movement of the vehicle in the rearward direction)" is outputted, when it is actuated to a "N (neutral)" position, a select lever signal representative of "parking and initiating of engine start" is outputted and when it is actuated to a "D (drive)" position, a select lever signal signal representative of "forward movement" is outputted from the select lever device 10. Particularly, when the select lever 11 is located at the position "D" representing "forward movement", the engine 40 (precisely speaking, an electronic governor 41 incorporated in the engine 40) and the transmission 60 (precisely speaking, a solenoid valve 61 usable for the purpose of shifting gears) are controlled via the controller 30 so that automatic speed changing is effected within the range of, e.g., second speed to fifth speed. When the select lever 11 is actuated to a position representing "HOLD", a select lever signal representing "maintaining the gear position in the transmission 60 at this time point" is outputted from the select lever device 10. In this case, the gear position which has been selected via the solenoid valve 61 at this time point is maintained in the transmission 60. Namely, the vehicle is then caused to move while a constant speed stage which has been selected is maintained. In addition, when the select lever 11 is actuated to the position "HOLD", actuation of the select lever 11 in the direction of an arrow mark F2 in the drawing makes it possible to perform a manual speed changing operation. If the select lever 11 is actuated in the direction of, e.g., "DOWN", a select lever signal representing "manual shift down" is outputted from the select lever device 10, whereby the transmission 60 is brought in meshing engagement with speed reduction gears. If the select lever 11 is actuated in the direction of "UP", a select lever signal representing "manual shift up" is outputted from the select lever device 10, whereby the transmission 60 is brought in meshing engagement with speed increase gears. In connection with the select lever device 10, reference numeral 13 designates an inching switch for commanding movement of the vehicle at a very low speed by a depressing operation without actuation of an acceleration pedal, reference numeral 14 does an "ECON (economy)" switch for commanding so-called economic movement of the vehicle by a depressing operation, reference numeral 15 does a "PWR (power)" switch for commanding so-called powerful movement of the vehicle (movement of the vehicle with high output) by a depressing operation and reference numeral 16 does a "1st (first)" switch for commanding start of movement of the vehicle at a first speed at the "D" position of the select lever 11 by a depressing operation. Fig. 2 is a flowchart which summarily illustrates a manner of performing the aforementioned controlling operation in relation to the hold processing of the automatic speed changing apparatus (particularly, the controller 30), i.e., a processing to be performed when the select lever 11 is actuated to the "HOLD" position. As shown in Fig. 2, with the automatic speed changing apparatus as described above, the hold processing is executed under conditions that speed changing is controlled unless the select lever 11 is actuated to the "HOLD" position and the select lever 11 is actuated by no means in the direction of the arrow mark F2 once it has been actuated to the "HOLD" position. The hold processing permits the current speed stage of the transmission 60 (which has been selected at this time point) to be maintained, as mentioned above. When the select lever 11 is shifted to the "R" position during the hold processing, i.e., when movement of the vehicle is shifted from F (forward movement) to R (rearward movement), the hold processing is naturally canceled, whereby automatic speed changing is performed while the "rearward movement" state is maintained, unless the select lever 11 is actuated to the "HOLD" position again. When the select lever 11 is actuated further in the direction of the arrow mark F2 while it is actuated to the "HOLD" position, "manual speed changing" is performed in the direction of shift-down or in the direction of shift-up in correspondence to the direction of actuation of the select lever 11, as mentioned above. Since the automatic speed changing apparatus assures that movement of the vehicle can excellently be stabilized by virtue of the hold function provided in that way and moreover fatigue of a driver (operator) can be minimized, the automatic speed changing apparatus is very significant for a passenger car, a truck or the like vehicle of which movement is comparatively few shifted from forward movement to rearward movement and vice versa but employment of the automatic speed changing apparatus is still problematical for a construction machine such as a wheel loader or the like which is designed and constructed in the form of a vehicle having tires used therefor in the same manner as the aforementioned vehicles. Specifically, since a construction machine such as a wheel loader or the like is such that its movement is often shifted from F (forward movement) to R (rearward movement) and vice versa, as will be apparent from consideration of its utilization, employment of the automatic speed changing apparatus for the construction machine leads to the following malfunctions. Accordingly, a work can not be conducted at a high efficiency in spite of employment of the automatic speed changing apparatus. 1) Although the automatic speed changing apparatus can be held at a specific speed stage suitable for conducting a certain work, this hold state should be canceled soon (per every shifting operation from F to R and vice versa). 2) Once the hold state is canceled, it is required that movement of the vehicle is once shifted up to the preceding speed stage and then a hold processing (representing a processing of actuating the select lever 11 to the "HOLD" position) is performed again in order that the automatic speed changing apparatus is held at the preceding speed stage again. 3) A holding processing to be repeatedly performed per every shifting operation from F to R and vice versa is very complicated and incorrect operation is liable to occur. It is the object of the present invention to provide an automatic speed changing apparatus for a vehicle in the form of a construction machine such as a wheel loader or the like which assures that a hold processing can always be executed at a high efficiency while a load to be carried by an operator (driver) is reduced. This problem is solved, according to the invention, with the features of claim 1. According to the present invention, switch means, i.e., a hold switch for making a designation as to whether a hold processing should be executed or not is provided for a controller of the automatic speed changing apparatus independently of actuation levers in the form of a select lever or the like so that the controller executes a hold processing, i.e., a processing of automatically holding a gear position (speed stage) in the transmission which has been selected at this time point. Consequently, once a required speed stage has been held by actuating the hold switch, movement of a vehicle can immediately be achieved in an automatic manner at the required speed stage merely by shifting movement of the vehicle from forward movement to rearward movement and vice versa. This enables an operation to be performed at a high efficiency using a construction machine such as a wheel loader or the like vehicle. Further, according to the present invention, in case where movement of the vehicle is shifted from forward movement to rearward movement and vice versa after the hold switch is actuated, when it is automatically shifted to the required speed stage which has been held in that way, i.e., when the vehicle starts its movement in accordance with a "hold" mode irrespective of forward movement or rearward movement, the transmission is once forcibly shifted to a second speed stage (representative of a shift change), and thereafter when movement of the vehicle reaches the required speed stage which has been held as the vehicle speed is increased, the hold processing is executed so as to automatically hold this speed stage. Consequently, when the vehicle moves at the required speed stage after movement of the vehicle is shifted from forward movement to rearward movement and vice versa, shifting to the required speed stage can always be achieved stably and smoothly. Fig. 1 is a view schematically illustrating by way of system diagram a conventional automatic speed changing apparatus employable for a vehicle, Fig. 2 is a flowchart illustrating performing a plurality of processings, particularly a hold processing using the automatic speed changing apparatus shown in Fig. 1, Fig. 3 is a perspective view illustrating an actuating section and a section to be controlled in the automatic speed changing apparatus for a vehicle in accordance with an embodiment of the present invention, Fig. 4 is a view schematically illustrating a manner of arranging a variety of sensors in case where the automatic speed changing apparatus is employed for a wheel loader, Fig. 5 is a block diagram illustrating by way of example the electrical structure of portions relating mainly to a hold processing to be performed by the automatic speed changing apparatus, Fig. 6 is a flowchart illustrating a manner of performing mainly a hold processing ("hold" mode processing") in the automatic speed changing apparatus and Fig. 7 is a view schematically illustrating an automatic speed changing apparatus in accordance with other embodiment of the present invention in case where the present invention is applied to the conventional apparatus (system) as shown in Fig. 1. Now, the present invention will be described in detail below with reference to the accompanying drawings, particularly, Figs. 3 to 6 which illustrate an embodiment thereof. This embodiment will be described below on the assumption that a wheel loader is employed as a vehicle to which the present invention is applied. For the reason, an automatic speed changing apparatus according to the illustrated embodiment will be described hereinafter as an apparatus for automatically controlling a speed changing operation in relation to a speed of movement of the wheel loader. Fig. 3 is a perspective view which schematically illustrates the structure of a driver seat section and objects to be controlled in a wheel loader, i.e., a transmission section to be controlled by the automatic speed changing apparatus of the present invention. In Fig. 3, numeral 101 designates a steering handle, reference numeral 110 does a lever device, reference numeral 111 does a forward/rearward shifting lever arranged on the lever device 110 to perform a shifting operation of shifting from F (forward movement) to R (rearward movement) of a vehicle and vice versa as represented by arrow marks in the drawing, reference numeral 112 does a speed stage shifting lever likewise arranged on the lever device 110 to perform a shifting operation of shifting to a required speed stage for the vehicle as represented by arrow marks in the drawing, reference numeral 113 does an automatic speed changing/manual speed changing shifting lever provided at the fore end of the speed stage shifting lever 112 to perform a shifting operation from an "automatic speed changing" mode to a "manual speed changing" mode and vice versa in response to an ON-OFF actuation of the speed stage shifting lever 112, reference numeral 120 does an acceleration pedal, reference numeral 120S does an acceleration pedal position detecting sensor for detecting a position assumed by the acceleration pedal 120, reference symbol ST does a driver's seat, reference numeral 170 does a working machine actuating lever arranged in the proximity of the driver's seat ST and reference numeral 180 does a hold switch arranged likewise in the proximity of the seat ST to issue a command to a controller (precisely speaking, a solenoid valve driving circuit) to be described later in response to the ON-OFF actuation of the speed stage shifting lever 112 as to whether the hold mode processing, i.e., a processing of automatically holding the gear position (representative of the speed stage) which has been selected at this time point by a transmission 160 as shown in Fig. 3 should be executed or not. Incidentally, reference numeral 161 designates a solenoid valve mounted on the transmission 160 to shift the gear position (speed stage) in the transmission 160. The forward movement/rearward movement shifting lever 111 is provided with a sensor 111S for detecting the current shifted position and the speed stage shifting lever 112 is provided with a sensor 112S for detecting the current shifted position (in practice, these sensors 111S and 112S being incorporated in the lever device 110), although they are not shown in Fig. 3. Specifically, the speed stage shifting lever 112 is used for both modes, 1.e., "automatic speed changing" mode and "manual speed changing" mode, and in case where the speed stage shifting lever 112 is actuated to, e.g., a position "3", an automatic speed changing operation can be performed within the range comprising a first speed stage, a second speed state and a third speed stage depending upon a quantity of depressing operation of the acceleration pedal 120, while in case where the speed stage shifting lever 112 is actuated to, e.g., a position "2", an automatic speed changing operation can be performed within the range comprising a first speed stage and a second speed stage depending upon a quantity of depressing operation of the acceleration pedal 120. Similarly, in case where the speed stage shifting lever 112 is actuated to other position, the range in which an automatic speed changing operation is performed can be set in the same manner in conformity with the aforementioned rule. Fig. 4 schematically illustrates how essential components inclusive these various sensors and switches constituting the automatic speed changing apparatus are arranged in the wheel loader and how they are operatively associated with each other. In Fig. 4, reference numeral 130 designates a controller, reference numeral 137 does a solenoid valve driving circuit to be controlled by the controller 130, reference numeral 140 does an engine, reference numeral 142 does an engine speed detecting sensor for detecting the current engine speed, reference numeral 150 does a clutch and reference numeral 162 does a vehicle speed detecting sensor for detecting the current speed of movement of the wheel loader. Other components and units have been already described above. Fig. 5 illustrates a structure of the automatic speed changing apparatus by showing how the aforementioned components and units are electrically connected to each other and Fig. 6 illustrates by way of flowchart a manner of performing operations in connection with the aforementioned hold mode processing. Structure and operations of the automatic speed changing apparatus will be described below with reference to Figs. 5 and 6. Informations on detected positions derived from the forward movement/rearward movement shifting lever position detecting sensor 111S, the speed stage shifting lever position detecting sensor 112S and the acceleration pedal position detecting sensor 120S are converted into digital signals by A/D (analogue/digital) converters 191, 192 and 193 so that they are inputted into the controller (computor) 130. Additionlly, the content of actuations of the automatic speed changing/manual speed changing shifting switches 113 and the hold switch 180 is likewise inputted into the controller 130 in the form of a binary signal. The controller 130 is operated such that these inputted signals are introduced into an arithmetic circuit (CPU) 133 via a first input interface 131. On the other hand, detected informations derived from the vehicle speed detecting sensor 162 and the engine speed detecting sensor 142 are converted into digital signals by A/D converters 194 and 195 so that they are inputted into the controller 130. The controller 130 is operated such that these inputted signals are introduced into the arithmetic circuit 133 via a second input interface 132. The arithmetic circuit (CPU) 133 is a circuit in which a variety of signals inputted via the input interfaces 131 and 132 in accordance with a processing program previously stored in a program memory 134 are processed as required and the solenoid valve driving circuit 137 for driving the transmission shift solenoid 161, an electronic governor (not shown) for controlling a rotational speed of the engine 140, a solenoid valve (not shown) for turning on and off the clutch 150 and other associated components are controlled so as to match the content of actuations of the levers 111 and 112, the pedal 120 and the switches 113 and 180 executed by an operator. Control signals outputted from the arithmetic circuit 133 are transmitted via an output interface 135 to respective circuit to be controlled. A hold data memory 136 incorporated in the controller 133 is a memory in which when the hold switch 180 is shifted to an ON side, control data to be given to the solenoid valve driving circuit 137 from the arithmetic circuit 133 at this time point, i.e., a speed stage command to be issued at this time point is stored. While the hold switch 180 is shifted to the ON side in that way, the subsequent controlling and processing are executed in the arithmetic circuit 133 in accordance with the manner as represented by a step 5 and subsequent steps in a flowchart shown in Fig. 6. Specifically, as shown in Fig. 6, in case where the automatic speed change/manual speed change shifting switch 113 is shifted to, e.g., an OFF side so that "manual speed changing" is designated, the arithmetic calculating circuit 133 makes a determination that the automatic speed changing has been designated (step 1 in Fig. 6) so that controlling and processing are executed in accordance with a hitherto known "manual speed changing" mode in response to detection of an actuation position of the speed stage shifting lever 112 (step 2 in Fig. 6). In case where the hold switch 180 is shifted to the OFF side while the switch 113 is shifted to the ON side to designate "automatic speed change" (step 1 in Fig. 6), the arithmetic circuit 133 makes a determination that the hold switch 180 has been shifted to the OFF side (step 3 in Fig. 6), controlling and processing are executed in accordance with "automatic speed changing" mode on the basis of the automatic speed change range designated and set by the speed stage shifting lever 112 in the above-described manner in response to detection of a depressing position of the acceleration pedal 120 (step 4 in Fig. 6). However, in the case where the hold witch 180 is shifted to the ON side in that way while the switch 113 has been already shifted to the ON side, the arithmetic circuit 133 stores in the hold data memory 136 control data (speed stage command) to be given to the solenoid valve driving circuit 137 at this time point and then controls the solenoid valve driving circuit 137 in conformity with control data to be later stored in the hold data memory 136. This permits a speed stage selected in accordance with the current mode, i.e., "automatic speed changing" mode at this time point to be maintained in the transmission 160 (step 5 in Fig. 6). When forward movement/rearward movement is shifted via the forward movement/rearward movement shifting lever 111 while such "hold" mode is maintained, the arithmetic circuit 133 makes a determination that the forward movement/rearward movement has been shifted in that way (step 6 in Fig. 6). Then, when the vehicle starts its movement (either of forward movement and rearward movement), the transmission shifting solenoid valve 161 is first controlled via the solenoid valve driving circuit 137 so that the transmission 160 is forcibly shifted and changed to a second stage (step 7 in Fig. 6). Thereafter, controlling is executed for acceleration and selection of speed stage in accordance with "automatic speed changing" mode in correspondence to an extent of depressing of the acceleration pedal 120 until a control command value to be given to the solenoid valve driving circuit 137 reaches the command value (control data) stored in the hold data memory 136 (step 8 in Fig. 6). When the control command value to be given to the solenoid valve driving circuit 137 reaches the command value stored in the hold data memory 136, the arithmetic circuit 133 makes a determination that the control command value has reached the command value stored in the hold data memory 135 and thereafter the program automatically goes to the processing at the step 5, i.e., a processing of controlling the solenoid valve driving circuit 137 in accordance with the control data (control command value) stored in the hold data memory 136. Such processing to be executed by the arithmetic circuit 133 continues until the hold switch 180 is disconnected, i.e., until the hold switch 180 is shifted to the OFF side. Thus, with the automatic speed changing apparatus as constructed according to the embodiment, a hold processing is brought in such a state that it automatically continues in response to actuation of the hold switch 180. Thereafter, speed of the vehicle is automatically changed to the movement speed at a required speed stage which has been held in that way, when movement of the vehicle is shifted from forward movement to rearward movement and vice versa. Consequently, with the automatic speed changing apparatus of the present invention, any operation can be performed at a high efficiency with an operator's load reduced remarkably using a vehicle such as the illustrated wheel loader or the like of which movement is often shifted from forward movement to rearward movement and vice versa. Further, with the automatic speed changing apparatus of the present invention, in case where movement of the vehicle is shifted from forward movement to rearward movement and vice versa after the hold switch 180 is actuated, shift control (shift change) is once forcibly carried out to a second speed stage, when the current speed stage is automatically shifted to a required speed stage which has been held in that way, i.e. when the vehicle starts its movement in accordance with the "hold" mode irrespective of forward movement or rearward movement. Thereafter, when the speed stage reaches a required speed stage which has been held in that way as the vehicle speed is increased, the speed stage is automatically maintained at the above required speed stage by executing the hold processing. Consequently, when vehicle movement is attained at the required speed stage after the vehicle movement is shifted from forward movement to rearward movement and vice versa, shifting to the required speed stage can always be performed stably and smoothly. Incidentally, this embodiment has been described above with respect to an automatic speed changing apparatus on the assumption that a rotational speed of the engine 140 is controlled by means of an electronic governor but the present invention should not be limited only this. Alternatively, the engine may be controlled by employing other suitable method. Further, it should of course be understood that the present invention should not be limited only to the foregoing unit. According to the embodiment, detection is made by the acceleration pedal position detecting sensor 120S as to whether the vehicle is held at the moving state or not but such detection can practically be made by monitoring the rotational speed of the engine 140. In case where recognition is additionally made on the basis of a detection signal generated by the engine speed detecting sensor 142, the automatic speed changing apparatus may be constructed with the acceleration pedal position detecting sensor 120S and the A/D converter 193 removed therefrom. For the convenience of description, structure and operation of the automatic speed changing apparatus have been described above as to the case where the embodiment of the present invention is applied to the existent steering apparatus as well as the existent automatic speed changing apparatus employable for a wheel loader or the like vehicle. However, the present invention can likewise be applied to the automatic speed changing apparatus as shown in Fig. 1. One example will be shown in Fig. 7. Specifically, with the automatic speed changing apparatus shown in Fig. 7, a select lever device 10' is a device adapted to issue a command as to one of "R (rearward movement)", "N (neutral)" and "D (forward movement)" as well as "automatic speed changing" mode or "manual speed changing" mode in the same manner as the select lever device 10 in Fig. 1, when the vehicle starts its movement. A difference point from the select lever device 10 shown in Fig. 1 consists in that the select lever device 10' does not have a function of commanding a hold processing as mentioned above. A command as to whether a hold processing is required or not is issued in response to actuation of a hold switch 180 arranged separately. In the case of the select lever device 10', it is assumed that only a command for the "manual speed changing" mode is issued, when a select lever 11 is shifted to a "MANU" position (representing a manual position). In Fig. 7, reference numeral 170 designates a working machine actuating lever as described hereinbefore. The working machine actuating lever 170 is removed from the automatic speed changing apparatus in case where the vehicle is a passenger car, a truck or the like. In this automatic speed changing apparatus, a controller 30' has functions equal to those of the controller 30 according to the preceding embodiment shown in Fig. 5 so that when a "hold" mode is designated via the hold switch 180, a step 6 and subsequent steps as shown in Fig. 6 which represents a flowchart are repeatedly executed in the same manner as in the preceding embodiment. Accordingly, also with the automatic speed changing apparatus shown in Fig. 7, an operation can be performed at a high efficiency with an operator's load remarkably reduced using a vehicle such as a wheel loader or the like of which movement is often shifted from forward movement to rearward movement and vice versa. When the vehicle moves at a required speed stage which has been previously held, shifting to the required speed stage can always be effected stably and smoothly. With respect to each of the aforementioned embodiments, a position where the hold switch 180 is located and a manner of arranging the hold switch 180 can be determined arbitrarily. Provided that the position and the manner are determined such that the hold switch 180 can be actuated independently of other actuating levers, the hold switch 180 may be arranged at any position in accordance with any manner. The foregoing embodiments have been described above as to the case where a computor is used as a controller and a series of controlling operations for automatic speed changing inclusive a hold processing are executed using the computor. Alternatively, the computor may, of course, be constructed in the form of a so-called hardware circuit so that the same controlling operations for automatic speed changing as mentioned above are executed using the hardware circuit. As will be apparent from the above description, according to the present invention, movement of a vehicle can immediately be achieved in any case in an automatic manner at a required speed stage which has been previously determined. Thus, a work can be performed at a high efficiency using a construction machine such as a wheel loader or the like of which movement is repeatedly shifted from forward movement to rearward movement and vice versa.

Claims: An automatic speed changing apparatus for a vehicle, including at least an actuating lever (110), the actuating lever (110) comprising a forward movement/rearward movement shifting lever (111) for shifting the movement of the vehicle from the forward movement to the rearward movement and vice versa and a speed stage shifting lever (112) for shifting the speed stages of the vehicle, an accelerating pedal (120) and switch means (180) adapted to be actuated independently of the actuating lever (110) and the accelerating pedal (120), the apparatus executing, when the actuating lever (110) is actuated to a given speed stage of the forward movement side, automatic speed changing corresponding to an extent of depressing of the accelerating pedal (120) within a range from a first speed stage to the given speed stage to which the actuating lever (110) is being actuated and, when the switch means (180) is actuated to an ON side while the actuating lever (110) is being actuated to the given speed stage of the forward movement side, storing the given speed stage and then automatically maintaining the stored speed stage as an upper limit speed stage for the automatic speed changing of the vehicle until the switch means (180) is actuated to an OFF side, characterized in that the speed stage shifting lever (112) is capable of setting the speed stage to any one of the speed stages under the same condition with respect to the actuation of the forward movement/rearward movement shifting lever (111) either to the forward movement side and the rearward movement side, and that the apparatus comprises controlling means (130), when the switch means (180) is actuated to the ON side while the speed stage shifting lever (112) is being actuated to the given speed stage, for executing the automatic speed changing corresponding to the extent of depressing of the accelerating pedal (120) to the stored speed stage under the same condition regardless of the forward movement or the rearward movement in accordance with the actuation of the forward movement/rearward movement shifting lever (111). The apparatus as set forth in claim 1, characterized in that, when the forward movement/rearward movement shifting lever (111) is actuated to other side while the switch means (180) is being actuated to the ON side, the controlling means (130) first forcibly controls the speed stage to a second speed stage regardless of an actuation position of the speed stage shifting lever (112) at this time point and thereafter shifts up the speed stage to the stored speed stage as time elapses following the acceleration of vehicle speed corresponding to the extent of depressing of the accelerating pedal (120).

Inventors: FUKUDA MASAO, FUKUDA, MASAO
Applicants: KOMATSU MFG CO LTD, KABUSHIKI KAISHA KOMATSU SEISAKUSHO
Application year: 1989
Main classification: B60K20
IPC codes: F16H59, F16H61, F16H63, B60K20, E02F9, B60W30