Abstract:
A motor vehicle is provided with a cab, an engine located laterally with respect to the cab, an engine transmission operatively connected to the engine, and a telescopic lift arm which, in a front working position, is located between the cab and the propulsion mechanism. The front and rear axles receive motive power from a pair of propeller shafts. A power transfer device of a substantially rectilinear shape is provided between the engine transmission and the pair of propeller shafts. The power transfer device is defined entirely by a number of gears.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a motor vehicle with a telescopic lift arm and, particularly to motor vehicles in which the telescopic lift arm, when operated at the front of the vehicle, is below the line of sight of the driver of the vehicle. Conventionally, such a lowered position corresponds to an all-round visibility of the driver in the cab. 
     As is known, to be able to lower the telescopic lift arm without restricting the line of sight of the driver, solutions have been adopted in which the vehicle engine is located on a first longitudinal side of the vehicle while the cab is located on a second longitudinal side, opposite to the first. The lift arm is lowered into a central recess formed in the vehicle body between the cab and the engine. The hydraulic assembly powering the telescopic arm is normally located at the rear of the vehicle. It will be appreciated that the central position of the telescopic arm and the hydraulic assembly powering the arm provides for a perfect load balance when operating the arm. 
     One of the problems posed by this type of vehicle is that the engine positioned on the lateral side of the cab must, for construction reasons, be located higher than the propeller shafts transmitting motion to the front and rear axles. With respect to the ground, the engine in fact is located at substantially the same height as the driver&#39;s cab, while the propeller shafts are traditionally located beneath the level of the cab. The main reason for this kind of arrangement lies in the fact that the engine and the device for transmitting motion from the engine to the universal joints of the propeller shafts having to be located substantially higher than the two propeller shafts to avoid being damaged when traveling over rough ground. 
     The above arrangement therefore poses the problem of providing a reliable system for transmitting motion between shafts—the output drive shaft of the engine and the propeller shafts—located at two different heights with respect to the ground. In addition, such a transmission system must also be located substantially beneath the recess in the vehicle body for receiving the telescopic arm in the lowered position. 
     One attempt to solve the above problem is described in U.S. Pat. No. 5,478,192, in which a motor vehicle is discussed having a telescopic lift arm, and wherein the cab and engine are located conventionally on opposite sides of the longitudinal axis of symmetry of the vehicle. A system for transmitting motion between the drive shaft coming out of the engine transmission and the propeller shafts is provided comprising two chains arranged in series. An inherent problem of such an arrangement is the creation of vibrations during drive transmission, and a poor reliability of the system as a whole. Moreover, in as much as the motion transfer case containing the chains sits on top of the engine transmission, the resultant overall length of the combined engine/transmission structure necessitates to spread the front and rear axles strongly apart, which badly influences the maneuverability of the vehicle. 
     Moreover, to get under the side member of the vehicle, the above system calls for dividing the motion transfer case into two chain housings inclined at an angle with respect to each other. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an object of the present invention to provide a motor vehicle having a telescopic lift arm and which is designed to eliminate the aforementioned drawbacks. 
     It is another object of this invention to provide in a motorized vehicle, between the engine transmission and a pair of propeller shafts, a power transfer device of a substantially rectilinear shape. 
     These and other objects, features and advantages are accomplished according to the instant invention in which a motor vehicle is provided with a cab, an engine located laterally with respect to the cab, an engine transmission operatively connected to the engine, and a telescopic lift arm which, in a front working position, is located between the cab and the propulsion mechanism. The front and rear axles receive motive power from a pair of propeller shafts. A power transfer device of a substantially rectilinear shape is provided between the engine transmission and the pair of propeller shafts. The power transfer device is defined entirely by a number of gears. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The advantages of this invention will become apparent upon consideration of the following detailed disclosure of the invention, especially when taken in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is a side elevational view, with some parts removed, of a motor vehicle having a telescopic lift arm; 
     FIG. 2 shows a cross section of the motor vehicle of FIG. 1; 
     FIG. 3 shows a plan view of the motor vehicle of FIGS. 1 and 2 illustrating the location of the engine with respect to the front and rear propeller shafts; 
     FIG. 4 schematically shows the gear train defining the engine transmission and the device for transmitting motion from the transmission to the two propeller shafts; 
     FIG. 5 shows a side view of the transmission device in the above drawings combined with the engine transmission; 
     FIG. 6 shows a front view of the whole arrangement defined by the engine transmission and the transmission device; and 
     FIG. 7 shows a plan view of the transmission device and the engine transmission as shown in the above drawings. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A motor vehicle  1  with a telescopic lift arm  3 , incorporating the principles of the instant invention can be seen in FIG.  1 . Any left and right references are used as a matter of convenience and are determined by standing at the rear of the machine  1 , facing forward into the direction of travel. 
     Vehicle  1  includes a body  2  supported by a frame capable of supporting the weight of an arm  3 , which comprises two telescopic portions  3   a ,  3   b  and is powered by a hydraulic drive assembly  4  located at the rear of the vehicle  1 . 
     Vehicle  1  also includes a cab  5  housing a driver&#39;s seat  6  and a steering wheel  7 . As shown more clearly in FIGS. 2 and 3, cab  5  is mounted laterally with respect to a longitudinal axis of symmetry A of vehicle  1  extending through center-line points P 1  and P 2  of respective axles  9  and  10  (FIG.  3 ). An engine  8  is mounted on the other side of longitudinal axis of symmetry A for simultaneously powering front axle  9  and rear axle  10  via a transmission defined respectively by a front propeller shaft  11  and a rear propeller shaft  12  (FIG.  3 ). Axles  9  and  10  are conventionally fitted with respective traction wheels  9   a ,  9   b  and  10   a ,  10   b . Propeller shafts  11 ,  12  are connected by respective universal joints  13 ,  14  to a power transfer device or transmission device  15  which, in innovative manner and as will be seen later on, acts as a go-between between an engine transmission  16  and the universal joints  13 ,  14  which, as seen, transmit motion to front axle  9  and rear axle  10  respectively. 
     As shown in FIG. 1, a longitudinal axis of symmetry B of the engine drive shaft  8   a  lies in a horizontal plane S 2  substantially parallel to a plane S 1  containing longitudinal axis of symmetry A. Both planes S 1  and S 2  are substantially parallel to, but at different levels with respect to the ground So. More specifically, plane S 2  is higher than S 1 , so that, as intended, all the significant mechanical parts as regards transmission of motion between engine  8  and propeller shafts  11 ,  12  are located substantially above plane S 1 , thus greatly reducing the risk of seriously damaging engine  8 , transmission device  15 , and/or transmission  16 , in the event, for example, of one of the front wheels  9   a ,  9   b  or the rear wheels  10   a ,  10   b  accidentally sinking into the terrain. 
     In the embodiment of the invention depicted in FIGS. 4-7, the transmission device  15  is located downstream from transmission  16  with respect to the transmission of motion from engine  8  to propeller shafts  11 ,  12 . Together, the transmission device  15  and the transmission  16  define an innovative, transmission unit  100 . 
     As shown in FIG. 4, the transmission  16 , which is mechanical, is defined conventionally by a number of gears which mesh selectively to obtain a number of different ratios as requested by the driver. In FIG. 4, the gears of the transmission  16  are shown meshing in first forward gear. The transmission  16  further is of a conventional design and therefore not described in detail. 
     As shown in FIG. 4, shaft  16   a  of the transmission  16  is fitted with the last gear  16   b  of the transmission  16 , and transmits motion, via a joint  16   c , to a shaft  17   a  fitted with the first gear  15   a  of the transmission device  15 . 
     As shown in FIGS. 4 and 6, device  15  comprises a casing  17  (FIG. 6) for supporting a number of shafts  17   a - 17   d  fitted with respective gears  15   a - 15   d  arranged in series and defining a gear train extending from the last gear  16   b  of the transmission  16  to the two universal joints  13 ,  14  integral with shaft  17   d  of the last gear  15   d . By means of the universal joints  13 ,  14 , motion is transmitted to the propeller shafts  11 ,  12  and then to the drive wheels  9   a ,  9   b  and  10   a ,  10   b  respectively. As best seen in FIG. 6, the shafts  17   a - 17   d  all extend in the previously defined plane S 1 . 
     As shown in FIG. 6, the transmission  16  of unit  100  has an axis of substantial symmetry C lying in a plane of substantial symmetry S 3 , which advantageously, though not necessarily, slopes at an angle of 45° with respect to parallel planes S 1 , S 2 , whereas device  15  extends substantially parallel to the horizontal plane S 1 . In other words, whereas device  15  extends substantially horizontally, the transmission  16  slopes at an angle of 45°. 
     The advantages of a device  15  and a unit  100  in accordance with the present invention will be clear from the foregoing description. Foremost is the advantage of eliminating, for example, the chains of known transmission systems, thus reducing the occurrence of vibrations and improving reliability of the system as a whole. Moreover, the shape of unit  100  provides for raising engine  8  with respect to ground So and lowering propeller shafts  11 ,  12  to conveniently transmit motion to wheels  9   a ,  9   b  and  10   a ,  10   b . As such, the risk of collision between delicate elements such as the engine  8 , the transmission unit  100 , etc. with rough contours of the ground So, are greatly reduced. 
     The particular shape of unit  100  also provides for achieving the compactness and reliability essential to vehicle  1 . With particular reference to FIGS. 3 and 4, the transmission device  15  taps rotative power from the engine transmission  16  at shaft  16   a , through which drive is transmitted in a rearward direction, i.e. opposite to the direction in which driving power enters the transmission  16  from the engine  8 . Consequently, no extra space is required for the transmission device  15  on top of the engine transmission  16 , reducing the overall length of the engine structure, whereby the spacing between the front and rear wheels  9   a ,  10   a  thus can be kept to a minimum, sufficient to house the combined engine/transmission structure. 
     Furthermore, as best seen in FIG. 6, the proper choice of the inclination of plane S 3  and the dimension of the gears employed in the transmission  16  ensure that shaft  16   a  substantially coincides with plane S 1 , enabling the transmission device  15  to be oriented in a horizontal position. Due to the inclination of plane S 3 , the output of the transmission  16  is offset from the vertical, longitudinal plane through the engine  8  in the direction of the axis of symmetry A. As a result, the transmission device  15  is kept relatively short. Again by properly choosing the dimensions of the gears  15   a - 15   d , the output shaft  17   d , to which the universal joints  13 ,  14  are connected, substantially coincides with the axis of symmetry A. All of this results in a compact and simple, but nonetheless reliable transmission of power from the engine  8  towards the propeller shafts  11 ,  12 . 
     Moreover, the particular shape of the transmission unit  100  provides for getting underneath the side member of the frame without having to disrupt the shape of said side member. This is extremely important in terms of construction by enabling the use of a frame comprising two identical, straight side members, one right and one left, requiring no recesses in the vehicle body. Automated production of the two side members is therefore simplified considering that they can be identical as regards their longitudinal sides. 
     It will be understood that changes in the details, materials, steps and arrangements of parts which have been described and illustrated to explain the nature of the invention will occur to and may be made by those skilled in the art upon a reading of this disclosure within the principles and scope of the invention. The foregoing description illustrates the preferred embodiment of the invention; however, concepts, as based upon the description, may be employed in other embodiments without departing from the scope of the invention. Accordingly, the following claims are intended to protect the invention broadly as well as in the specific form shown.