referring to the drawings and firstly to fig1 and 2 , there is illustrated a truck assembly 10 according to an embodiment of the invention primarily designed for use with longboard skateboards but which may be used with smaller size skateboards or any other similar rideable vehicle . the truck assembly 10 includes a main truck body 11 which is adapted to be mounted to the underside of the deck of a skateboard via a mounting block 12 which may be secured by bolts , screws or fasteners to the skateboard deck and with or without an intermediate spacer 13 . complementary coupling means are provided on the truck body 11 , mounting block 12 and spacer 13 which allow them to be slidably interengaged . thus the truck body 11 may be slidably engaged directly with the mounting block 12 or the truck body 11 may be slidably engaged with a spacer 13 which is slidably engaged with the mounting block 12 . thus spacers 13 of different thickness may be provided to enable different spacings of the truck body 11 from the skateboard deck . the complementary coupling means comprise a rib and groove type coupling comprising a pair of opposite parallel ribs or edges 14 and 14 ′ on the lower side of the truck body 11 and spacer 13 and a pair of opposed parallel grooves 15 and 15 ′ on the upper side of the spacer 13 and mounting block 12 . the ribs 14 and 14 ′ and grooves 15 and 15 ′ are at substantially the same lateral spacing such that the truck body 11 may be slid longitudinally onto the mounting block 12 or spacer 13 through the cooperation between the opposed ribs 14 or 14 ′ and grooves 15 or 15 ′ and similarly the spacer 13 may be slid longitudinally onto the mounting block 12 through the cooperation between the opposed ribs 14 ′ and grooves 15 ′. the truck body 11 is maintained in engagement with the mounting block 12 or spacer 13 by latching devices comprising a latching member 16 and 16 ′ on a spring or resilient finger 17 and 17 ′ fixed to the mounting block 12 or spacer 13 . the latch members 16 and 16 ′ are adapted to locate in a recess 18 on the underside of the truck body 11 and the latch member is adapted to located in a recess 18 ′ on the underside of the spacer 13 to retain the body 11 to the block 12 or spacer 13 , or spacer 13 to the mounting block 12 . the body 11 may be detached from the block 12 or spacer 13 or the spacer 13 may be detached from the mounting block 12 by pushing the free end of the finger 17 or 17 ′ downwardly to release the latch member 16 or 16 ′ from the recess 18 or 18 ′ to allow the truck body 11 to be slidably disengaged from the mounting block 12 or spacer 13 , or spacer 13 from the mounting block 12 . assembly is a reverse of the above except that the truck body 11 may be pushed onto the block 12 or spacer 13 until the latch member 16 or 16 ′ under the influence of the spring finger 17 or 17 ′ locates within the recess 18 and similarly for engagement of the spacer 13 with the mounting block 12 . the truck body 11 includes a transversely extending bore 19 which is sized to accept a steering adjustment boss 20 ( see also fig3 and 4 ) which is supported rotatably in the bore 19 by being inserted from one side thereof and which is retained by means of a circlip 21 on the opposite side such that the boss 20 is capable of rotation about the axis 22 of the bore 19 , that axis 22 extending substantially normal to the longitudinal axis of the skateboard deck to which the truck assembly 10 is mounted . the boss 20 may be journalled in the bore 19 or mounted via bearings therein . the boss 20 is also provided with a central bore 23 which is coaxial with the bore 19 of the body 11 . the bore 23 is of a somewhat rectangular configuration and receives the main truck axle 24 which supports at opposite ends via bearings the wheels 25 of the truck assembly 10 . the rectangular shape of the bore 23 accommodates pivotal movement of the truck axle 24 as described further below . the truck axle 24 is mounted to the boss 20 by means of a trunnions arrangement comprising a pair of opposite trunnions 26 ( see fig3 and 4 ) which are arranged intermediate the opposite ends of the axle 24 and which extend normal to the longitudinal axis of the axle 24 . the trunnions 26 may be defined by a pin inserted into a bore which extends transversely through the axle 24 and projects on opposite sides thereof . alternatively the trunnions 26 may be defined by a pair of pins which are provided on opposite sides of the axle 24 and interconnected for example by a threaded connection through the axle 24 . other arrangements however may be provided for defining the trunnions 26 . the trunnions 26 are supported in opposite bores 27 in the boss 20 via bearings 28 such as roller or ball bearings or bushes so as to allow for smooth pivoting movement of the axle 24 about the axis 29 of the trunnions 24 . the bores 27 may be closed on their outer sides by end caps . it will be apparent that in the position of fig1 the longitudinal axis of the axle 24 is coaxial with the axis 22 of the bore 19 . the orientation of the pivot axis 29 of the trunnions 26 can be adjusted however by rotation of the boss 20 in the bore 19 of the truck body 11 . to enable setting of position of the trunnions &# 39 ; s pivot axis 29 , an arm 30 which is integrally formed with the boss 20 extends radially from the boss 20 . the free end of the arm 30 is provided with a spring loaded stop pin 31 which is normally urged by an internal spring 32 in the arm 30 to the position of fig3 extending parallel to the axis 22 of the bore 19 . the pin 31 is provided with a head 33 to enable retraction of the pin 31 against the force of the spring 32 . the pin 31 may locate in one of a series of holes 34 provided at spaced apart positions along a curved member 35 of the body 11 which is centered on the rotational axis 22 of the boss 20 . to change the rotational position of the boss 20 relative to the truck body 11 , the pin 31 is retracted by grasping the pin head 33 and the arm 30 is then rotated in a desired direction to rotate the boss 20 arid reposition the stop pin 31 in alignment with another one of the holes 34 after which the pin 31 may be released to locate within that hole 34 to hold the arm 30 and boss 20 in a set position . it will be apparent that during this movement , axle 24 remains concentric with the axis 22 of the bore 19 . the boss 20 is also provided with relief grooves 36 and 37 extending from and on opposite sides of the bore 23 and in alignment with the arm 30 , the grooves 36 and 37 and the rectangular configuration of the bore 23 accommodating pivotal movement of the axle 24 in a plane 38 ( see fig4 ) perpendicular to the pivot axis 29 of the trunnions 26 . it will be appreciated that rotation of the steering boss 20 as described above will rotate the pivot axis 29 of the axle 24 as defined by the trunnions 26 to thereby vary the orientation of the plane 38 along which the axle 24 may pivot . to hold the axle 24 in a “ neutral ” position extending substantially at right angles to the truck body 11 and thus skateboard deck to which the truck assembly 10 is mounted , pairs of tension springs 39 are provided on opposite sides of the truck body 11 to extend between anchoring points 40 on the truck body 11 on either side of the axle 24 , and a lug 41 mounted to the axle 24 at a position spaced outwardly from the body 11 . the springs 39 provide a biasing force to resist pivotal movement of the axle 24 about the trunnions axis 29 . the springs are mounted at an angle to the axle in a triangular pattern so that their opposing resistance to the body weight needed to tilt the deck to produce turning remains reasonably constant for the range of deck angles . this is achieved by reducing the angle between the angle and the spring attachment or the truck body as the desk is tilted to adjust steering . the constant load assists in maintaining an even downward force on all four wheels during hard turning and hence optimised wheel grip . with conventional trucks the rubber or spring arrangement increases with deck angle and shifts the bodyweight downward force to the inside wheels , loading the wheels unevenly and reducing the overall wheel grip . the axle 24 preferably comprises a central part 42 which carries or is connected to the trunnions 26 and detachable opposite end parts 43 which carry the wheels 25 . the end parts 43 may be threaded for threaded engagement with opposite ends of the central part 42 with the spring mounting lugs 41 arranged therebetween . this arrangement also allows different length end parts 43 to be substituted or removed completely for different applications or for supporting wheels 25 of different sizes or configurations . as shown in fig5 and 6 , pairs of truck assemblies 10 are mounted at spaced apart fore and aft positions via respective mounting blocks 12 and spacers 13 ( if required ) to the underside of the deck 44 to form a skateboard 45 typically a longboard type skateboard . the positions of the steering bosses 20 of each truck assembly 10 may then be varied depending upon the steering characteristics required in the skateboard 45 . in the position shown in fig1 and assuming that the truck assembly 11 is mounted to the deck 44 of the skateboard 44 such that the pivot axis 29 is parallel to the longitudinal axis 46 of the skateboard 45 , pivotal movement of the skateboard deck 44 will not cause any steering movement of the truck assembly 10 as the axle 24 will pivot in a plane at right angles to the skateboard axis 46 . thus no fore and aft pivotal movement of the axle 24 results and thus no steering is achieved . altering the plane of pivotal movement of the axle 24 by inclining the axis 29 of the trunnions 26 to the longitudinal axis 46 of the skateboard 44 will enable steering to be achieved . thus if the arm 30 of the steering boss 20 is moved to a position where the stop pin 31 can locate in one of the holes 34 away from the central hole 34 ′ as for example shown in fig7 ( a ), the pivot axis 29 of the trunnions 26 is accordingly pivoted such as to be inclined to the longitudinal axis 46 . thus pivoting of the deck 44 as indicated by the arrows in fig7 ( c ) during riding of the skateboard 45 by for example weight shifting will be translated into a clockwise pivoting movement of the axle 24 as shown in fig7 ( b ) along the inclined plane indicated at 38 in fig7 ( a ) and therefore steer the skateboard 45 . where the skateboard deck 44 is pivoted in the opposite direction , the axle 24 will pivot in the inclined plane 38 in an anticlockwise direction to effect steering of the skateboard 45 in the opposite direction , if the arm 30 is further adjusted as shown in fig8 ( a ) to position the trunnions axis 29 at an increased angle to the longitudinal axis 46 of the skateboard 45 , the possible plane 38 of movement of the axle 24 will , relative to the axis 46 , become increasingly acute such that pivoting of the skateboard deck 44 as for example indicated by the arrows in fig8 ( c ) will result in increased fore and aft clockwise pivoting movement of the axle 24 and wheels 25 and thus sharper turning through a reduced turning circle . of course the steering effect of both the front and rear truck assemblies 10 may be selectively varied by simply readjusting the position of the arm 30 by retracting the stop pin 31 and repositioning the pin 31 in one of the holes 34 with movement of the pin 31 outwardly from the center position resulting in a reduced turning circle or a sharper steering effect with the same pivotal movement of the skateboard deck 44 . the rider is therefore able in a simple and effective manner to selectively adjust the steering required for different circumstances or different applications . in the skateboard 45 as illustrated in fig5 it will be seen that the steering adjustment arms 30 of the truck assemblies 10 are angled in opposite directions such that when the deck 44 is pivoted about the longitudinal axis 46 , the front and rear axles 24 will pivot in opposite directions . in some circumstances however it may be desirable to have only the front truck assembly 10 provide a steering function and thus the arm 30 of the rear truck assembly 10 in this instance is located in the central position as illustrated in fig1 where the deck of the skateboard 45 is planar . in the skateboard 45 of fig5 where opposite ends of the deck 44 are inclined upwardly , the arm 30 is adjusted such that it and the possible plane 38 of pivotal movement of the axle 24 are at right angles to the axis 46 the truck assemblies 10 of the invention may be applied to skateboard decks of many different configurations and various steering characteristics of the skateboard can be achieved by simply adjusting the adjustment arms 30 in the manner described . further handling characteristics can be varied by changing the spacers 13 or alternatively eliminating the spacers 13 . further it will be appreciated that other arrangements may be provided for supporting the axle 24 of the truck assembly 10 such that the angle of its possible plane of pivotal movement can be adjusted to adjust the steering characteristics of the truck assembly 10 . whilst the above has been given by way of illustrative embodiment of the invention , all variations and modifications thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of the invention as herein set forth .
a truck assembly for a skateboard , having a body for mounting to the underside of a skateboard deck . the body supports an axle and wheels mounted for pivoted movement for steering and includes adjustment means for varying steering characteristics of the skateboard . the axle may be mounted by a pair of opposite trunnions which define a pivot axis for the axle . the pivot axis is adjustable by a rotatable boss , preferably with a pivot arm which may be locked in place by a spring loaded pin inserted into a selected aperture . the truck may include two pairs of angled springs which are arranged similar to adjacent sides of a triangle and adapted to centre the axle . the truck assembly may include a removable spacer locatable between the deck and axle and extension pieces for the axle .