Controller device for wheeled construction machine
BACKGROUND OF THE INVENTION 
     1. Field of the Invention: 
     This invention relates to a controller device for a wheeled construction machine, having a variable speed lever capable of electrically controlling a transmission near a steering wheel. 
     2. Description of the Prior Art: 
     An electric controller device for a transmission is known to the art as disclosed in the specification of Japanese Patent Publication No. SHO 52(1977)-17,303, for example. It has already found utility in wheeled construction machines. 
     In the conventional wheeled construction vehicles such as the wheel loader, the variable speed lever disposed productingly beside the steering column is manually manipulated to effect required transmission control. Where the variable speed lever is of a column shift type and the variable speed lever is positioned at a large distance from the steering wheel, the operator of the vehicle is required to operate the variable speed lever, the steering wheel, and the vehicle control lever interchangeably, particularly during the work of excavation. During change of speed, the operator grips the steering wheel in his right hand and manipulates the variable speed lever in his left hand. For manipulation of the vehicle control lever, he now grips the steering wheel in his left hand and uses his right hand for the control of the vehicle. This system has the disadvantage that the operation thereof is complicated and is deficient in safety. 
     SUMMARY OF THE INVENTION 
     An object of this invention, therefore, is to provide a controller device for a construction machine, which enables the operator to use his left hand in gripping the steering wheel and the fingers of the same left hand in manipulating the variable speed lever and his right hand exclusively in controlling the vehicle control lever so as to eliminate the compexity of operation and improve the safety. 
     To attain the object described above, this invention provides a controller device for a wheeled construction machine, which comprises a combination switch box disposed adjacent the top of a steering column, a variable speed lever for electrically controlling steps of speed of a transmission disposed on the left side of the combination switch box, the variable speed lever being of a length so that the leading end thereof protrudes from the periphery of the steering wheel, a control lever for turning on and off various lamps disposed protrudingly on the right side of the combination switch box, and at least one of the variable speed lever and the control lever being attached to the combination switch box. 
     The other advantages, features, and objects of the present invention will become apparent to those skilled in the art upon making reference to the following detailed description and accompanying drawings in which preferred embodiments of the present invention are shown by way of illustration. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view illustrating a typical embodiment of this invention. 
     FIG. 2 is a magnified side view of the neighborhood of a steering wheel. 
     FIG. 3 is a plan view of the steering wheel. 
     FIG. 4 is a lateral cross section of a combination switch box. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Now, a typical embodiment of this invention will be described in detail below. In the drawings, a steering wheel 1 is provided for such a construction machine as a wheel loader. It is attached adjacent the upper end of a steering shaft 1a enclosed in a steering column 3 tiltable about a fulcrum 2. A combination switch box 4 is attached to the upper end of the aforementioned steering column 3. This combination switch box is formed in the shape of a rectangular box divided vertically into two parts. A lower case 4a is given a tightly closed construction owing to a partition 4c interposed between upper and lower cases 4a, 4b. This lower case 4a contains therein an assortment of switches (not shown). Two variable speed levers 5, 6 protrude from one lateral part of the upper case 4b. Of these two levers 5, 6, the former 5 is used for selection between forward and rearward travels and the latter 6 for selection among speed steps. They are supported on their respective basal sides within the upper case 4b through the medium of pivots 5a, 5b. These variable speed levers 5, 6 are such that their operation in the circumferential direction along the periphery of the steering wheel 1 actuates the switches disposed, though not illustrated, inside the lower case 4a and consequently effects electric-hydraulic control of the transmission which is connected, though not illustrated, to the switches. A stopper 14 is disposed nearby. 
     The aforementioned levers 5, 6 have lengths enough for their leading ends to protrude slightly from the periphery of the steering wheel 1 so that they may be operated by the finger tips of the operator&#39;s hand keeping a grip of the steering wheel 1. Moreover, the two levers 5, 6 are disposed at a short distance from each other so that they may be operated simultaneously. Their distances from the steering wheel A, FIG. 2, are limited roughly in the range of 30 to 100 mm. As the result, the vehicular speed can be safely changed. Since the levers 5, 6 are small and light as compared with their conventional counterparts, they can be operated lightly with the operator&#39;s finger tips. They are, therefore, not required to possess any appreciably high strength and their supporting parts do not require reinforcement. From the other lateral side of the upper case 4b is projected a control lever or switch lever 7 which is capable of being moved longitudinally, X, FIG. 3, and vertically Y, FIG. 2. When the control lever 7 is moved in the longitudinal direction, a winker switch contained, though not illustrated, within the lower case 4a is set to turn on or off a winker lamp. A self-cancelling mechanism 8 is disposed near the seat of the aforementioned control lever 7 inside the upper case 4b. The self-cancelling mechanism 8 serves to enable the control lever 7 which has been moved forward or rearward to be returned automatically to its neutral position by giving to the steering wheel 1 a turn in the direction opposite the direction in which the steering wheel 1 has been rotated so far. Owing to this arrangement, the possibility of the winker lamp being left blinking through the operator&#39;s negligence is precluded. Moreover, this winker switch is not affected by rainwater and other similar weather conditions because it is contained in a tightly closed lower case 4a. The aforementioned control lever 7 is provided at the leading end thereof with a rotatable knob 9. By rotating this knob 9, as indicated by the arrow Z, FIG. 3, a head lamp switch and a parking lamp switch contained, though not illustrated, inside a neck part are switched to turn on and off head lamps and parking lamps. By vertically moving the control lever 7, the head lamp can be switched between upward and downward tilt. Since the head lamp and the parking lamp are switched by one and the same knob 9, there is attained the advantage that the parking lamp left glowing through the operator&#39;s negligence is turned off without fail when the head lamp is turned on. 
     A knob 10 of a hazard lamp switch (not shown) protrudes from the front side of the lower case 4a. By this knob 10, the hazard switch disposed inside the lower case 4a can be controlled. 
     A corrugated tube 11 for wiring and connectors 12, 13 are conveniently disposed. Thus, the combination switch box incorporated in the present system contributes to simplifying the work of wiring. 
     Obviously, many modifications and variations of the present invention are possible in light of the preceding teachings. It is therefore to be understood that within the scope of the appended claims, the present invention may be practiced otherwise than as specifically described herein.