the following is intended to provide a detailed description of examples of the invention and should not be taken to be limiting of the invention itself . rather , any number of variations may fall within the scope of the invention , which is defined in the claims following the description . fig3 a is a perspective view diagram showing a general embodiment of a skateboard 300 constructed according to principles of the present invention . skateboard 300 includes a board 301 having a front caster assembly 302 mounted on a first end 303 of the board 301 , and a rear truck assembly 304 mounted on a second end 305 of board 301 , both assemblies being mounted on the underside of board 301 which is an elongate board or single deck that defines a board plane . front caster assembly 302 includes caster fork 314 , caster wheel 316 , and caster axle 318 , while rear truck assembly 304 includes truck mount 306 , truck axle 308 , first wheel 310 , and second wheel 312 . advantageously , a rider of skateboard 300 does not have to leave skateboard 300 to propel the board . in a preferred embodiment , skateboard 300 is designed such that drive is created with somewhat of a falling forward sensation that a rider may experience upon operating skateboard 300 . as illustrated , and as will be described in greater detail herein , front caster assembly 302 includes a caster with a caster pin at an angle with respect to the first end 303 of elongate board 301 . the caster pin allows the front caster assembly 302 to freely pivot on skateboard 300 . further , unlike prior art skateboards , the combination of front caster assembly 302 , adjacent to first end 303 of board 301 , and rear truck assembly 304 , adjacent to second end 305 of board 301 , provides an unexpectedly stable skateboard with an unexpected snow board / surf board feel . fig3 b is a perspective view diagram showing another general skateboard embodiment , skateboard 350 , constructed according to principles of the present invention . unlike skateboard 300 , skateboard 350 includes a truck assembly ( front truck assembly ) 352 and a caster assembly ( rear caster assembly ) 354 , both assemblies being mounted on the underside of an elongate board . as illustrated and as will be described in greater detail herein , rear caster assembly 354 includes a caster at an angle that is free to pivot on skateboard 350 . regardless of which skateboard 300 , 350 is constructed , the skateboard includes a caster assembly that is mounted at an angle . specifically , the caster mounting bolt ( aka , caster pin , see fig7 for a detailed descriptive embodiment ) is mounted at an angle and is not perpendicular or even required to be substantially perpendicular to the skateboard deck . fig3 c is a perspective view diagram showing a scooter embodiment having a three - wheel arrangement constructed according to principles of the present invention . fig3 c illustrates skateboard 300 constructed according to principles of the present invention , however , skateboard 300 includes a handlebar 370 to create a scooter embodiment . as understood by those of ordinary skill in the art when viewing fig3 c , the illustrated scooter embodiment may be constructed with many variations . for example , as discussed with regard to fig3 a , skateboard 300 could simply include a front caster assembly 302 and a rear truck assembly 304 , both assemblies being mounted on the underside of an elongate board or single deck . handlebar 370 allows a rider greater stability upon operation of skateboard 300 . fig4 a - c are perspective view diagrams showing a caster assembly embodiment that moves through different positions when the caster assembly operates according to embodiments disclosed in fig3 a , 3 b and 3 c . illustrated in fig4 a - c is front caster assembly 302 shown in three different pivot positions . fig4 a illustrates caster frame and fork 404 supporting caster wheel 402 freely rotatable about a caster axle . as illustrated in the following fig4 b - 4c , caster fork 404 translates radially about a caster pin , the caster pin being mounted at an angle with a board plane . further , caster fork 404 defines a caster angle , the caster angle defining an acute angle with respect to board plane . the caster angle may further define an acute angle with respect to the caster pin . fig5 is a perspective view diagram showing a removable caster assembly 500 that operates according to principles of the present invention . removable caster assembly 500 includes , similar to front caster assembly 302 , a caster wheel 502 freely rotatable about a caster axle . in addition , removable caster assembly 500 includes a caster frame and fork 504 that allows caster wheel 502 to translate radially about a caster pin . caster fork 504 defines a caster angle , the caster angle defining an acute angle with respect to a board plane . the caster angle may further define an acute angle with respect to the caster pin . as illustrated , the caster pin is at an angle with respect to the board plane . in addition , caster frame and fork 504 includes a base arrangement 506 for easily removing or attaching removable caster assembly 500 . in the illustrated embodiment of fig5 , removable caster assembly 500 is shown having apertures 508 spaced about base arrangement 506 . apertures 508 are intended to receive bolts 510 which can be adapted to securely affix removable caster assembly 500 to the board plane by means of fastening nuts 512 . upon viewing fig5 , it will be appreciated by those of ordinary skill in the art that other embodiments of removable caster assembly 500 such as a pin arrangement could be produced when skateboards of the invention such as skateboard 300 are studied . fig6 a is a perspective view diagram showing an adjustable caster assembly 602 that operates according to principles of the present invention . like the front caster assembly 302 of fig3 a , adjustable caster assembly 602 includes a caster wheel with caster frame and fork . a caster angle pin 604 when engaged with a base arrangement 606 is a preferred arrangement for securing the caster frame and fork into a particular angled position . as illustrated , angle pin 604 can be inserted at aperture 608 of base arrangement 606 in order to securely select a particular caster angle position . as will be appreciated by those of ordinary skill in the art upon viewing fig6 a , the different apertures of base arrangement 606 allow the caster wheel to be positioned at different angles with respect to the board plane . fig6 b is a profile view diagram showing adjustable caster assembly 602 when moved through different positions . adjustable caster assembly operates according to the embodiment disclosed in fig6 a . three separate positions for the caster wheel / fork are illustrated in fig6 b . each position is illustrated with a separate profile image in the drawing . of course , upon viewing the present disclosure , other angled embodiments may be illustrated as appreciated by those of ordinary skill in the art . fig6 c is a perspective view diagram showing adjustable caster assembly 602 as disclosed in fig6 a ; however , adjustable caster assembly 602 is combined with removable caster 500 disclosed in fig5 . specifically , base arrangement 606 is configured to allow the presence of apertures 508 spaced about base arrangement 606 for receiving bolts 510 which can be adapted to securely affix a now easily removable adjustable caster assembly 602 . removable and adjustable caster assembly 602 is affixed to the board plane by means of fastening nuts 512 . it will be appreciated by those of ordinary skill in the art upon viewing fig6 c that other embodiments of a removable adjustable caster assembly 602 could be produced within the scope of the present invention while yet including other aspects according to principles of the presently disclosed invention . fig7 a - c are perspective , profile , and cross - sectional view diagrams illustrating different views of an adjustable caster assembly 700 when the caster assembly operates according to embodiments disclosed in fig3 a . adjustable caster assembly 700 includes a caster fork supporting a caster wheel 702 , a caster plate 704 , and a caster base arrangement 706 . caster base arrangement 706 is illustrated having apertures 708 which enable removable caster functionality . caster base arrangement 706 is also shown having teeth 710 which enable the angle of caster assembly 700 to be securely adjustable when engaging caster lock plate 712 with caster assembly teeth 710 . in operation , as illustrated by the two - way arrows of fig7 a , caster plate 704 enables the caster fork with caster wheel 702 to freely pivot on an axis . in addition , engaging caster assembly teeth 710 with caster lock plate 712 enables caster wheel 702 to be securely and seamlessly adjusted relative to the board plane such that a preferred caster angle may be selected by a rider of a skateboard incorporating adjustable caster assembly 700 . fig7 b illustrates a profile view of adjustable caster assembly 700 . the profile view shows two positions that a rider may set caster wheel 702 . these two positions are shown in different line formats . one position is shown with solid lines , while a second position is shown with dashed lines ; dashed lines are used in order to illustrate the second position that a rider of skateboard 300 may select for a skateboard constructed according to principles of the disclosed invention . fig7 c illustrates a profile and cross - sectional view of an embodiment of an adjustability mechanism for adjustable caster assembly 700 . for clarification purposes , caster base arrangement 706 is illustrated showing multiple views and hence multiple label numbering . for example , in the profile portion of the drawing , caster base arrangement 706 is illustrated and in the cross - sectional view , caster assembly teeth 710 are illustrated on caster base arrangement 706 . caster assembly teeth 710 are shown engaging with teeth of caster lock plate 712 . also shown in fig7 c is a detailed cross - sectional view of caster plate 704 and related hardware for implementing an embodiment of adjustable caster assembly 700 . caster plate 704 is coupled to caster lock plate 712 by the tension of caster plate retaining bolt ( aka , caster mounting bolt or caster pin ) 722 threaded into said caster lock plate 712 . caster plate 704 rotates freely due to caster retaining bolt 722 engaging caster radial bearing 718 on the inner race . outer race of caster radial bearing 718 engages the caster plate 704 . caster thrust bearing 720 suspends caster plate 704 above caster lock plate 712 . as will be appreciated by those of ordinary skill in the art when viewing caster assembly 700 , caster block 714 may be secured with caster lock nut 716 to secure a caster pin angle when caster assembly 700 is configured to allow selection of a caster pin angle by a rider of skateboard 300 . further , the caster fork may attach to caster plate 704 via simple welding , manufacturing caster plate 704 having forks included as a single part , or other similar attachment method . the included functional descriptive material is information that imparts functionality to a machine . this functional descriptive material includes , but is not limited to , mechanical gearing of an apparatus such as adjustable caster assembly 700 . while particular embodiments of the present invention have been shown and described , based upon the teachings herein , it will be appreciated by those skilled in the art that changes and modifications may be made without departing from the principles of this invention and its broader aspects . therefore , the appended claims are to encompass within their scope all such changes and modifications as are within the true spirit and scope of this invention . furthermore , it is to be understood that the invention is defined by the appended claims . it will be understood by those with skill in the art that if a specific number of an introduced claim element is intended , such intent will be explicitly recited in the claim , and in the absence of such recitation no such limitation is present . for non - limiting example , as an aid to understanding , the following appended claims contain usage of the introductory phrases “ at least one ” and “ one or more ” to introduce claim elements . however , the use of such phrases should not be construed to imply that the introduction of a claim element by the indefinite articles “ a ” or “ an ” limits any particular claim containing such introduced claim element to inventions containing only one such element , even when the same claim includes the introductory phrases “ one or more ” or “ at least one ” and indefinite articles such as “ a ” or “ an ”; the same holds true for the use in the claims of definite articles .
a method for propelling a skateboard . the method includes applying an alternating lateral force to first and second sides of a first end of the skateboard . the skateboard first end is offset from a second end of the skateboard , and the first and second ends define a board plane . the skateboard includes a truck assembly and a caster assembly . the caster assembly has a caster pin at an angle with respect to the board plane . other embodiments are also disclosed .