as shown in fig1 through 8 , 11 through 14 , and 16 , preferred embodiments of our invention are built in and around a chassis 10 consisting of upstanding left and right side walls 11 , front end wall 12 and rear end wall 13 , all erected about the periphery of an extended horizontal floor 19 . the front end wall has a forward protrusion 14 which supports and contains functional connections for a small light bulb 26 , and which also supports a transparent light distributor 51 . details of the bulb 26 , distributor 51 , and related features are presented in the above - mentioned patent and will not be repeated here . the front end wall 12 also has a generally rectangular slot 15 , 16 formed in it . the rear end wall 13 has a similar slot 17 , 18 . these slots are for use in aligning the mechanism cover 60 , which also is discussed in detail in the previously mentioned patent and will not be further discussed here , although some minor differences may arise -- principally due to the greater width of the present mechanism . the slots 15 , 16 , and 17 , 18 also function in journaling certain rotating portions of the mechanism . this too is accomplished substantially as described in the previous patent , though the number of rotating parts is larger . the chassis 10 serves both as a frame to support and as a partial enclosure to conceal and protect the power source and train . mounted below the chassis for rolling rotation with respect to it are two mutually parallel but spaced - apart axles , an axle 36 near the front and an axle 46 near the rear of the chassis . secured to the ends of these two axles 36 and 46 are respective pairs of rotary driving means -- front tread drivers 237 and rear tread drivers 247 , which are thus in effect mounted to the frame for rolling rotation about respective mutually parallel but spaced - apart axes ( the centerlines of the axles 36 and 46 ), one such axis being in front of the other . continuous - belt treads 937 are looped over , suspended between , and preferably driven by both of the drivers . mounted atop the chassis floor 19 at a position between the two axles ( or tread driver rotation axes ) is an electric motor with housing 27 . the motor housing 27 is located against one of the side walls 11 , and oriented so that its driveshaft 283 ( fig3 and 4 ) is perpendicular to the two tread - driver - rotation axes . this motor is of a type whose driveshaft extends both fore and aft from the motor housing . the motor housing 27 is secured against longitudinal motion by two blocks 319 , which are integral with the chassis floor 19 and the adjacent side wall . mounted to the two ends of the motor driveshaft 283 are respective &# 34 ; drive pinions &# 34 ; or &# 34 ; drive gears &# 34 ; ( we mean these terms to be interchangeable ) 31 at the front and 41 at the rear , which are firmly secured for rotation witn the driveshaft . below and to the left ( taking the direction of vehicle motion as &# 34 ; straight ahead &# 34 ;) of the drive pinions 31 and 41 and meshed with them are respective spur gears 32 and 42 , which rotate on corresponding shafts 35 and 45 oriented parallel to the driveshaft . the spur - gear shafts 35 and 45 are each journalled at one of their respective ends into one of the motor blocks 319 , and at the other of their respective ends into the corresponding end wall 12 or 13 . sharing the spur - gear shafts 35 and 45 with the spur gears 32 and 42 , and firmly secured to those spur - gear shafts to rotate with them , are respective worms 33 and 43 . we prefer to make the spur gears 32 and 42 and the corresponding worms 33 and 43 as respective integral assemblies , or spur - gear - and - worm clusters : one such cluster 32 - 33 thus has a spur - gear section 32 and worm section 33 , and the other cluster 42 - 43 has a spur - gear section 42 and worm section 43 . similar spur - gear - and - worm clusters 32a - 33a and 42a - 43a are also provided . these additional clusters are respectively positioned adjacent and parallel to the already discussed spur - gear - and - worm clusters 32 - 33 and 42 - 43 . each of the additional clusters 32a - 33a and 42a - 43a is journalled at one of its ends into one of the motor blocks 319 , and at the other of its ends into the corresponding end wall 12 or 13 . with the addition of these additional clusters 32a - 33a and 42a - 43a , the fore and aft ends of the drive mechanism remain symmetrical . it may be noted , however , that they are not identical to each other but rather are mirror images : the first - mentioned ( high mechanical advantage ) clusters 32 - 33 and 42 - 43 are &# 34 ; outboard &# 34 ; or toward the left in both ends of the mechanism , while the additional ( low mechanical advantage ) clusters 32a - 33a and 42a - 43a are &# 34 ; inboard &# 34 ; or toward the right . the spur - gear sections 32a and 42a of these additional clusters 32a - 33a and 42a - 43a are driven from the respective adjacent spur - gears 32 and 42 of the outboard clusters 32 - 33 and 42 - 43 . this drive arrangement causes the inboard clusters 32a - 33a and 42a - 43a to rotate in the opposite direction from the first - mentioned or outboard clusters 32 - 33 and 42 - 43 . accordingly , since the object of the inboard clusters 32a - 33a and 42a - 43a is to drive the respective worm gears 34 and 44 in the same direction though with different mechanical advantages , the worm sections 33a and 43a are opposite in &# 34 ; handedness &# 34 ;-- that is , they are of opposite pitch -- relative to the outboard clusters 33 and 43 respectively . below these pairs of clusters , and oriented and disposed to mesh with the worm sections 33 and 43 , are respective worm gears 34 and 44 -- each oriented to rotate about axes parallel to the axes of tread driver rotation . the worm gears 34 and 44 and the respective tread driver pairs 237 and 247 are mounted conaxially ( that is , together on the same respective axles 36 and 46 ). whereas the tread driver pairs 237 and 247 are fixed to their respective axles 36 and 46 , however , the worm gears 34 and 44 are keyed to their respective axles 36 and 46 . this may be accomplished , for example , by providing the gears 34 and 44 with respective hubs 434 and 444 ( fig5 and 6 ) that have square central holes ( fig4 ), and providing the axles 36 and 46 with matching square cross - sections . thus the worm gears 34 and 44 rotate with , but can slide along , the axles 36 and 46 . the worm gears 34 and 44 in fact can slide along their respective axles 36 and 46 into engagement with either of the respective worms : the front - end worm gear 34 can engage either the worm section 33 of cluster 32 - 33 , or the worm section 33a of cluster 32a - 33a ; while the rear - end worm gear 44 can engage either the worm section 43 of cluster 42 - 43 , or the worm section 43a of cluster 42a - 43a . the result of sliding the worm gears 34 or 44 between worm sections in this way is to select different values of mechanical advantage between the motor driveshaft 238 and the tread drivers 237 and 247 . the difference may be regarded as derived from the additional gear - train stages represented by mutually engaged spur - gear sections 32 and 32a , at one end of the chassis , and mutually engaged spur - gear sections 42 and 42a at the other end of the chassis . thus each of the worm gears 34 and 44 drives a respective pair 237 or 247 of tread drivers , but with mechanical - advantage values that depend upon the positions along the axles 36 and 46 of the worm gears 34 and 44 , relative to the worm sections 33 and 33a at the front of the chassis , and 43 and 43a at the rear . fig6 and 9 show a detent mechanism consisting of an arm 491 extending from the shifting element 425 - 425a , and dimensioned to be &# 34 ; springy &# 34 ; in the direction fore and aft of the vehicle , and a triple - notched structure 492 formed in the housing floor 19 and positioned to engage the arm 491 . this mechanism is dimensioned and located to provide three stable positions for the shifting element 425 - 425a , in which positions , respectively , the worm gears are ( 1 ) engaged with the low - mechanical - advantage worms , or ( 2 ) engaged with the high - mechanical - advantage worms , or ( 3 ) disengaged entirely . it is to be understood that the three positions in our preferred embodiment do not exist in the order just stated , the disengaged position being the middle one ; and that it is within the scope of our invention to provide the three positions in any order . the tread drivers 237 and 247 , as well as the axles 36 and 46 themselves , must rotate relative to the housing walls 11 -- even though the axles 36 and 46 are square . if desired , the tread drivers 237 and 247 may be provided with externally cylindrical but internally square bushings , fitted snugly over the square ends of the axles 36 and 46 , but rotating smoothly in cylindrical holes formed in downward extensions of the chassis walls 11 ( see fig5 through 8 ). we have found , however , that such bushings need not be provided , and an economy can therefore be realized , if the axles 36 and 46 and the housing walls 11 are made of suitable materials and suitably configured . in particular , we have found that with drawn steel axles -- having smooth , rounded corners -- and with housing walls 11 made of hard plastic such as the materials known commercially as abs or &# 34 ; delrin ,&# 34 ; there is insignificant wear of the housing walls , the loads involved being quite light . in this way the tread drivers may be driven by a symmetrical power train having only two or three stages and yet providing a choice between very high mechanical advantage and only moderate mechanical advantage , between the motor driveshaft and the axles . this versatile power train occupies a narrow space along one side of the chassis 11 -- and thus leaves the greater width of the chassis for a &# 34 ; penlight &# 34 ; battery 21 ( whose positive pole appears at 23 ) and the appropriate electrical connectors 22 and 24 . as to the battery polarity , the motor connections , and the &# 34 ; handedness &# 34 ; or pitch direction of the worms used in our invention , it is to be understood that any two of these factors may be reversed and the toy vehicle will operate in the same direction . for instance , if the battery polarity is reversed and the handedness of the worms is also reversed , the vehicle will still move &# 34 ; forward &# 34 ; as defined by the front / rear terminology used in this document . from the fact that the dry - cell battery 21 appearing in fig1 is only a size - aa penlight type , the remarkably small overall size of the vehicle may be seen dramatically . yet , due to the simplicity of the novel drive train , it is possible to obtain the two modes of operation described earlier , and without highly miniaturized or high - precision gears . the point at which shifting and disengagement is effected in the described mechanism -- that is , the functional location of the shiftable and disengageable worm gears 34 and 44 -- is &# 34 ; downstream &# 34 ; in the power train from the worms 33 , 33a and 43 , 43a respectively . hence the mechanism has the added advantage , noted earlier , of providing a freely operable &# 34 ; rolling neutral .&# 34 ; the worms 33 , 33a and 43 , 43a are respectively &# 34 ; downstream &# 34 ; in the power train from additional gear - reduction stages composed of the drive pinions or spur gears 31 and 41 in combination with the spur - gear sections 32 , 32a and 42 , 42a of the spur - gear - and - worm clusters . hence the mechanism has the further advantage , also noted earlier , of operating the worms 33 , 33a and 43 , 43a at relatively low speeds for better operating efficiency . the disengageable and shiftable worm gears 34 and 44 , moreover , are at the final , lowest - rotational - velocity point in the power train . hence the mechanism has the yet further advantage of &# 34 ; shifting &# 34 ; the lowest - speed gears available , and thereby minimizing clash and wear . fig1 through 14 illustrate another embodiment of the power - train features of our invention . this embodiment too has all of the foregoing advantages . subject to slight reservations it may be regarded as a variant that is equally preferred with the embodiment already discussed . these drawings are representative of both ends of the mechanism , though with a mirror - image form of duplication as encountered in the previously discussed embodiment . here the pinion or driver gear 741 is lengthened so that it can engage continuously both ( 1 ) the spur - gear section 742 of the low - speed spur - gear - and - worm cluster 742 - 743 and ( 2 ) the spur - gear section 742a of the high - speed spur - gear - and - worm cluster 742a - 743a . both clusters are thus driven in common directly from the driver 741 , whereas in the previously described embodiment the corresponding high - speed cluster 42a - 43a was driven from the spur section 42 of the low - speed cluster 42 - 43 as an intermediate . examination of the drawings will reveal that the resulting speeds of the respective high - speed clusters 42a - 43a and 742a - 743a ( i . e ., their angular velocities ) are identical . they are identical because the intermediate spur 42 transmits the pinion rotation &# 34 ; 1 : 1 &# 34 ;-- that is , without any gearing change -- to the high - speed cluster . since the intermediate spur 42 introduces a reversal of rotational sense , however , the directions of high - speed cluster rotation are opposite for the two configurations . in the embodiment of fig1 through 15 the worms 743a and 743 consequently rotate in the same direction , rather than in opposite directions as do the worms 43 and 43a of the first - discussed embodiment . the handedness or pitch of the two worms 743a and 743 , therefore , is the same rather than opposite . the various other elements of the variant embodiment in fig1 through 15 are essentially the same as those in the drawings relating to the first - discussed embodiment . accordingly the detailed discussion of these other features is not repeated here . some preference for the first - discussed embodiment may arise from the slight protrusion of the low - speed spur section 742 , in the variant embodiment , toward the battery compartment ; however , this may well be overcome by minor rearrangements of the parts . a miniature scale - model vehicle body ( such as 74 in fig2 ) is fitted to the chassis 10 . the body 74 snaps on and off to permit easy changing of the battery 21 , as generally described in the previously mentioned patent . the body style may be designed from &# 34 ; fantasy ,&# 34 ; or may be derived from a real vehicle body , with some adjustment of proportions to fit the chassis . the toy vehicle of the previously mentioned patent was uniquely adapted for operation on steep surfaces such as portion 83 of the toy terrain shown in fig2 and over vertical steps taller than its own tread driver radius , such as that at 86 in fig2 and on surfaces that are irregular , or both steep and irregular . the toy vehicle of our present invention is also operable on all such surfaces , by virtue of its plural selectable mechanical - advantage values . the toy vehicle of our present invention , however , is also operable in a satisfying mode of play on generally flat and regular surfaces such as portion 85 of the terrain in fig2 . to obtain excellent traction , the treads 937 can be provided with extremely exaggerated cleats . some details of the construction of this preferred embodiment of our invention include protective worm - gear wells , such as the rear well 73 , encasing the worm gears 34 and 44 respectively , and drive - mechanism cover 60 . the wells such as rear well 73 must be wider than the corresponding structures appropriate to the invention of the earlier - mentioned patent , because the wells in the present case must accommodate the lateral motion of the worm gears 34 and 44 along their axles . the journalling of the spur - gear - and - worm clusters into the chassis , at the ends of the clusters that are remote from the motor housing , may be accomplished as indicated in the previously mentioned patent , or in other convenient ways . the electrical switching mechanism of our present invention is in part novel . battery 21 applies power through contacts 22 and 24 ( fig3 , 9 , and 10 ) to the light bulb 26 and motor 27 in parallel . the rear - end metal contact 22 is fixed to the housing floor 19 by means of a self - tapping screw 22a . this contact 22 is extended along the side of the battery to metallic contact 422 , which contacts the bottom of the motor housing 27 to complete the circuit , but only ( as will be described in detail ) when the worm gear is engaged with one of the worms . the other metal contact 24 is similarly secured to the housing floor by a similar screw 24a ; soldered at 24b to this contact 24 is the bared conductive end of an insulated length of wire 224 , whose remote end engages an appropriate contact point on the motor . the novel aspect of this mechanism resides in the use of a single manual control to effectuate ( 1 ) selection of mechanical advantage , or ( 2 ) disengagement of the tread drivers from the gearing entirely , and ( 3 ) completion or interruption of the electrical connections , depending upon whether the control is in position to select a nonzero value of mechanical advantage in accordance with choice number ( 1 ), or in position to disengage the tread drivers in accordance with choice number ( 2 ). as can be seen from fig9 and 10 , the contact strip 22 , 422 is pinned to the chassis floor 19 by means of another self - tapping screw 428 , which is threaded into a hole 419 formed in the floor 19 . the floor 19 is thickened at this point , to provide sufficient thread length for secure attachment of the screw 428 , by formation of a boss 429 -- which extends both downward and upward relative to the nearby portions of the floor 19 . the upper extension of the boss 429 also forms a standoff and guide pin . the boss functions as a standoff in that it holds the contact strip 422 up away from the floor 19 proper . in the space thus formed between the strip 422 and the floor 19 fits the shifting element 425 , 425a . this shifting element defines a slot 526 , which is dimensioned to accept the guide - pin / standoff / boss 429 . the shifting element is retained between the floor 19 and the contact 422 . as shown , the shifting element 425 , 425a is made slightly thinner than the height of the upward extension of the boss 429 , so that the shifting element can slide smoothly between the floor 19 and the contact 422 . the shifting element extends and slides through apertures 411 ( fig1 ) in both side walls 11 , and has manually manipulable ends 425 and 425a that are -- when the shifting element is installed in the chassis 10 -- thus user - accessible near the bottom of the outside of the chassis 10 , at the left and right sides of the toy vehicle respectively . the shifting element also has shifting forks 534 and 544 ( fig6 and 9 ) that are sized and disposed to engage the worm gears 34 and 44 respectively , to drive the worm gears laterally ( along their respective square axles ) into engagement with the respective worms 33 , 33a and 43 , 43a -- or into an entirely disengaged intermediate position , for &# 34 ; rolling neutral ,&# 34 ; for the objectives previously indicated . the &# 34 ; dogleg &# 34 ; structure 525 of the shifting element is an advantageous arrangement for obtaining access to the worm gears 34 and 44 , to shift them , while clearing the bottom ends of the motor mounts 319 . the effectuating means mentioned earlier include all the provisions described in the foregoing three paragraphs . the overall result of these combined provisions is that a user may shift between the three modes of operation of the toy vehicle without picking the vehicle up , and using just one hand to move the shift element leftward or rightward between the stable positions of the detent mechanism . in particular , to shift the element from its leftward or central position toward the right , the user can : ( 1 ) place her or his left thumb ( or right index finger , if it is preferred to use the right hand ) against the right side of the vehicle body , above or next to the shift element end 425 but not obstructing the shift element end 425 ; ( 2 ) place the left index finger ( or right thumb , if the right hand is to be used ) against the left end 425a of the shift element ; and ( 3 ) squeeze the thumb and index finger together to complete the shifting . similarly , to shift the element from its rightward or central position toward the left , the user can place the left index finger ( or right thumb ) against the left side of the vehicle body , but positioned to avoid obstructing the shift element end 425a , and the left thumb ( or right index finger ) against the right end 425 of the shift element , and squeeze to complete the shifting . it is also possible to operate the shifting mechanism by holding the vehicle down with the palm of the hand or with one or more fingers , while pushing the shifting element laterally with one finger . we do not prefer this way of using the mechanism , because it does not yield the same degree of control as the way described in the preceding paragraphs , but it is within the scope of our invention . these ways of using the shifting element thus provides relative motion between that element and the other parts of the shifting mechanism , to actually effectuate the selection of mechanical advantage -- or , in other words , to actually effectuate the selection among plural operating modes . the word &# 34 ; manipulable &# 34 ; and the phrase &# 34 ; manipulable . . . with one hand only &# 34 ; are used in the appended claims to describe the suitability of the shifting element for use in this way -- that is , not merely that the shifting element can be manipulated , but that when it is manipulated it is effective ; it can be manipulated in with only one hand to obtain the relative motion required for selection of a mechanical advantage or operating mode . a dimple 523 ( fig6 , and 10 ) formed in the top surface of the shifting element 425 , 425a accommodates a mating dimple 423 formed in the contact element 22 , 422 , when the two are in alignment , permitting the motor - contact end 422 of the contact element to descend out of contact with the bottom of the motor housing 27 . this is the condition of the shifting and contact elements when the shifting element is in position to disengage the worm gears 34 and 44 from both of their respective mating worms , as previously described . when the shifting element is in position to engage the worm gears 34 and 44 with either of their respective mating worms , however , the dimple 523 in the top surface of the shifting element 425 , 425a is moved out of alignment with the dimple 423 in the contact element 22 , 422 , forcing the upturned end 422 of the contact element upward into contact with the bottom of the motor housing 27 . as shown in fig1 , tread drive may be provided in combination with a single - operating - mode , single - speed &# 34 ; climbing toy &# 34 ; that is otherwise as shown in fig1 ( and described in the corresponding text ) of the above - mentioned patent . in this embodiment , the features and advantages are those resulting from enhancement of the extraordinary &# 34 ; climbing - toy &# 34 ; features by the extremely exaggerated traction of the treads . these features and advantages are especially salient when the vehicle climbs over objects which a wheeled vehicle could simply straddle , fore to aft , and on which it would therefore &# 34 ; hang up .&# 34 ; these features in combination produce a &# 34 ; climbing - toy &# 34 ; operation which is unique by virtue of its extreme exaggeration . it is to be understood that all of the foregoing detailed descriptions are by way of example only , and not to be taken as limiting the scope of our invention -- which is expressed only in the appended claims .
this toy operates on continuous - belt treads that cooperate with other &# 34 ; climbing toy &# 34 ; features to provide extremely exaggerated ability to negotiate steep and / or rough surfaces . the car selectably operates : as a conventional electrically powered toy , at at least one speed , on a flat surface ; as an electrically powered &# 34 ; climbing toy &# 34 ; with particularly advantageous weight distribution , at at least one reduced speed with greater torque , on a steep and / or irregular surface ; or as an unpowered free - rolling toy vehicle . major weight components , particularly the battery and motor , are in a symmetrical , compact , balanced and relatively low arrangement -- at about the same height as the tread drivers . together with a speed - reduction mechanism they fill the toy &# 39 ; s housing . the speed - reduction mechanism preferably has front - and - rear duplicate gear trains : at each end , two worms that are both powered from the motor shaft but through different speed - reduction gears , and an axle - driving worm gear shiftable between the worms .