Tractor

Jan. 19, 1965

Μ. K. SHIELDS ETAL

TRACTOR

3,166,141

Filed July 15, 1960

Sheets-Sheet 1

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MORTON K. SHIELDS RUSSELL K. SHIELDS INVENTORS

KENDRICK, SCHRAMM &amp; STOLZY

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ATTORNEYS

Jan. 19, 1965

Μ. K. SHIELDS ETAL

TRACTOR

3,166,141

Filed July 15, 1960

Sheets-Sheet 2

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MORTON K. SHIELDS RUSSELL K. SHIELDS INVENTORS KENDRICK, SCHRAMM &amp; STOLZY

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ATTORNEYS

Μ. K. SHIELDS ETAL

TRACTOR

Jan. 19, 1965

Filed July 15, 1960

3,166,141

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MORTON K. SHIELDS RUSSELL K. SHIELDS INVENTORS

KENDRICK, SCHRAMM &amp; STOLZY

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ATTORNEYS

Jan. 19, 1965

Μ. K. SHIELDS ETAL

3,166,141

TRACTOR

Filed July 15, 1960

Sheets-Sheet 4

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ATTORNEYS

Jan. 19, 1965

Μ. K. SHIELDS ETAL

TRACTOR

3,166,141

Filed July 15, 1960

Sheets-Sheet 5

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MORTON K. SHIELDS RUSSELL/K. SHIELDS INVENTORS KENDRICK, SCHRAMM &amp; STOLZY

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ATTORNEYS

Μ. K. SHIELDS ETAL

TRACTOR

3,166,141

Jan. 19, 1965

Filed July 15. 1960

Sheets-Sheet 6

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MORTON K. SHIELDS RUSSELL K. SHIELDS INVENTORS KENDRICK, SCHRAMM &amp; STOLZY

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ATTORNEYS

Jan. 19, 1965

3,166,141

Μ. K. SHIELDS ETAL

TRACTOR

Filed July 15, 1960

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MORTON K. SHIELDS RUSSELL K. SHIELDS INVENTORS

KENDRICK, SCHRAMM &amp; STOLZY

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ATTORNEYS

Μ. K. SHIELDS ETAL

TRACTOR

Jan. 19, 1965

Filed July 15, 1960

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ATTORNEYS

Μ. K. SHIELDS ETAL

TRACTOR

Jan. 19, 1965

Filed July 15, 1960

3,166,141

Sheets-Sheet 9

49.

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MORTON K. SHIELDS russell^shields

KENDRICK, SCHRAMM &amp; STOLZY

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ATTORNEYS

3,166,141

Jan. 19, 1965

Μ. K. SHIELDS ETAL

TRACTOR

Filed July 15, 1960

Sheets-Sheet 10

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MORTON K. SHIELDS RUSSELL K. SHIELDS INVENTORS

KENDRICK, SCHRAMM &amp; STOLZY

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ATTORNEYS

3,166,141

Jan. 19, 1965

Μ. K. SHIELDS ETAL TRACTOR

Sheets-Sheet 11

Filed July 15, I960

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attorneys

3,166,141

Patented Jan. 19,1965

United States Patent Office

3,166,141 TRACTOR

Morton 1C. Shields, 7050 Yolanda, Reseda, Calif., and Russell K. Shields, Encino, Calif. (5735 Halbrent, Van Nays, Calif.)

Filed July 15,1960, Ser. No. 43,154

Claims. (Cl. 180—21)

This invention relates to towing devices, and more particularly, to tractors.

Although the present invention will have application in many fields to tow land vehicles both large and small, it has been found especially useful for parking house trailers and boat trailers and moving airplanes into and out of hangers.

The chief requirement of a tractor to be used to tow house trailers, boat trailers and airplanes is that it must be relatively small in size. This is true not only from the standpoint of economy, but also because it frequently becomes necessary to park such vehicles under conditions such that the vehicles themselves occupy most of the available parking space and little is left in which a tractor may be operated.

Although the requirement that a tractor for such vehicles should be small in size would seem to be easily met by simply miniaturizing any conventional type of tractor, several difficult problems present themselves if such an attempt is made. One of these problems relates to what may be defined as primary skid and secondary skid. Briefly, primary skid is that skid produced. in steering two wheels of a conventional four-wheeled vehicle in a manner such that the wheels lie generally in planes parallel to each other when the vehicle is steered into a turn. Primary skid can be eliminated by a complicated and rather heavy special steering transmission. However, secondary skid is inevitable in a turn due to the finite tread width of the wheels.

Primary skid can be completely eliminated by using a three-wheeled tractor. However, due to the wheel base, dimensions and weight of house trailers and airplanes especially, such a small three-wheeled tractor has the dangerous tendency to tip over.

Another requirement of a tractor useful for parking heavy vehicles, such as house trailers and airplanes, is that it must be able to turn from a 90° right turn to a 90° left turn and vice versa rapidly without substantial physical effort being involved... This means that if power is used in such a case, in order to keep the tractor small by keeping its engine small, such a turn -must be possible without the need for considerable power.

Still another requirement for moving house trailers is the use of a four-wheeled vehicle which will not tip over even in rugged terrain.

Although to the present time no prior art tractor for towing house trailers or boat trailers or airplanes has met any of the requirements set out hereinbefore, the device of the present invention does so by providing a chassis, a caster-type wheel mounted at each of the forward and rearward ends of the chassis, a driven wheel mounted on each side of the chassis, the driven wheels being fixed to shafts in position to rotate in respective longtudinal planes, and power means including a mechanical differential mounted on the chassis for rotating the driven wheels.

From the foregoing, it will be appreciated that primary skid is completely avoided by the use of front and rear caster-type wheels with a differential connected pair of center-driven wheels, whereas the tendency of the tractor of the invention to tip over is effectively eliminated by the use of four wheels. :.

In accordance with another outstanding feature of the present invention, a universal-type or ball and socket trailer hitch is employed. This means that the tractor of the present invention may be turned from a 90° right turn to a 90° left turn and vice versa without substantial 5 physical effort being involved and without the need for any mechanical power from the tractor engine whatsoever. This is true because the tractor of the present invention can be so turned without, in fact, moving a house trailer or the like which may be hitched to it at 10 the time only the tractor is turned. Note will be taken that the mechanical differential in combination with the trailer support position for the trailer hitch provides this advantage and that both are indispensable in this one regard. In this same regard, it is to be noted that the 15 use of a. universal-type trailer hitch, such as a ball and socket joint, is unusually useful when employed with the tractor of the present invention where sharp turns are required and especially on rough ground.

In turning, when power is supplied to the driven wheels, 20 it is also a feature of the present invention that each one of the driven wheels may be braked, independently of the other for steering.

Still another feature of the present invention resides in the construction of a tractor including a chassis, a 25 caster-type wheel mounted on the rearward end of the chassis, a driven wheel mounted on each side of . the chassis, the driven wheels being fixed to shafts in positions to rotate in the respective longitudinal planes, power means including a mechanical differential mounted 30 on the chassis for rotating said driven wheels, a U-shaped member having legs extending rearwardly toward the driven wheels in ah approximately horizontal plane, the U-shaped member having the ends of its legs mounted on the chassis to rotate about a horizontal transverse ?⁵ axis, a caster-type wheel suspended from the bight portion of the U-shaped member, and means to support the forward end Of the chassis movable oh the bight portion of the U-shaped member. Thus, on rough ground, the front wheel of the tractor of the present in⁴⁰ vention may be adjusted to ride over large bumps in the road.

In a similar regard, in accordance with one aspect of the invention, a tractor of a construction is provided including a chassis, a caster-type wheel mounted at each of the forward and rearward ends of the chassis, a driven wheel mounted on each side of the chassis, the driven wheels being fixed to shafts in position to rotate in respective longitudinal planes, and power means including a mechanical differential mounted on the chassis for . rotating said driven wheels.

It is a feature of the invention that a boat trailer tractor may be provided including a chassis, a castertype wheel mounted at the forward end of the chassis, ₅₅ a longitudinal member to extend rearwardly of the chassis, the longitudinal member being rotatable about its forward end, a caster-type wheel suspended from the rearward end of the longitudinal member, and detent means on the chassis to hold the longitudinal member 60 in a substantially horizontal position, the detent means being releaseable to permit rotation of the chassis upwardly at its forward end about the rotational axis of the driven wheels. Thus, a ball of the ball and socket'type trailer hitch on the tractor of the invention may be ro65 tated rearwardly and downwardly under the socket on a boat trailer and a hitching operation accomplished rapidly and without substantial effort.

The above-described and other advantages of the tractor of the present invention may be better understood from 7θ the following description considered in connection with the accompanying drawings.

3,166,141

- - .3

In the drawings, which are to be regarded as merely illustrative:

FIG. 1 is a perspective view of one embodiment of the invention;

FIG. 2 is another perspective view of the embodiment 5 shown in FIG. 1;

FIG. 3 is a top plan view of the tractor of the invention shown in FIGS. 1 and 2;

FIG. 4 is a sectional view of the tractor taken on the line 4—4 shown in FIG. 3; jq

FIG. 5 is a bottom plan view of the .tractor of the invention shown in FIGS. 1 to 4, inclusive;

FIGS. 6 and 7 are still other perspective views of the tractor of the invention illustrated in FIGS. 1 to 5, inclusive. 15

FIG. 8 is a sectional view taken on the line 8—8 shown in FIG. 7;

FIG. 9 is a sectional view of the tractor of the invention taken on the line 9—9 shown in FIG. 8;

FIG. 10 is a partly diagrammatic side elevational view 20 of the tractor of the invention shown in FIGS. 1 to 9, inclusive, illustrating an operational characteristic thereof;

FIG. 11 is a top plan view of a broken-away portion of the tractor made in accordance with another embodiment of the invention;25

FIG. 12 is a sectional view of the tractor taken on the line 12—12 shown in FIG. 11;

FIG. 13 is a side elevational view of a broken-away portion of the tractor made in accordance with another ~ embodiment of the invention;so

FIG. 14 is a sectional view of the tractor taken on the line 14—14 shown in FIG. 13; and

FIGS. 15 and 16 are perspective views of a portion of a tractor made in accordance with another feature of the invention.35

In the drawing in FIG. 1, a tractor 20, made in accordance with the invention, is illustrated having a chassis 21 on which is mounted an internal combustion engine and clutch assembly 22 having a housing 23. Neither the internal combustion engine nor the clutch is shown in detail, 40 both being conventional. The clutch is preferably a conventional centrifugal clutch which mechanically connects an output shaft to the internal combustion engine drive shaft upon the internal combustion engine drive shaft reaching a predetermined speed, the clutch output 45 shaft having a sheave thereon, to drive a sheave 24 fixed to an input shaft 25 to a transmission 26 by means of V-belts 27. The internal combustion engine output shaft, the clutch output shaft, and the sheave on the clutch output shaft are located in housing 23, all being conventional 50 structures. A muffler and exhaust assembly 28 is provided for the internal combustion engine which projects through an opening 29 in the wall of housing 23. As shown in FIG. 2, housing 23 is provided with a cylindrical extension 30 to surround a starting rope and drum assem- 55 bly, one end of the rope being connected to a handle grip 31 as is conventional.

The throttle of the internal, combustion engine has two cables connected to it indicated at 32 and 33, whereby the throttle of the internal combustion engine can be oper- 60 ated by the depression of either one of the right and left hand throttle buttons 34 and 35, respectively. Throttle buttons 34 and 35 are spring biased upwardly by springs 36 and 37, respectively. The wires of cables 32 and 33 are indicated at 38 and 39, respectively, in FIG. 1, the 65 sheaths of cables 32 and 33 being fixed relative to chassis 21 at 40 inside housing 23 and on the lower side of cylindrical end portions 41 and 42, respectively, surrounding a horizontally disposed shaft indicated at 43 in FIG. 3 which is fixed thereto to operate the transmission 26 as will be 70 explained hereinafter. Suffice it at this point to say that shaft 43 is rotatably mounted in bearings 44 and 45 as shown in dotted lines inside tubular handle bar extensions to the right and left of the tractor 20 indicated at 46 and 47, respectively, in FIG. 3, extensions 46 and 47 75

'. ⁴ being welded to the upper ends of tubular extensions 48 and 49, respectively, shown in both FIGS. 1 and 5 as being bolted to chassis 21 at 50 and 51, respectively.

A lever 52 is fixed to the throttle of the internal combustion engine and is biased by a helically coiled spring 53 having its lower end fixed relative to chassis 21 so that unless buttons 34 or 35 are forceably depressed, the throttle of the combustion engine remains almost closed.

Transmission 26 simply includes a three-to-one gear reduction with a gear shift operable to drive the tractor 20 forward or in reverse. As shown in FIG. 2, transmission 26 has input shaft 25 projecting outwardly therefrom as well as an intermediate shaft 54 and an output shaft 55 having a sprocket 56 fixed thereto. Around sprocket 56 a chain 57 is located which also surrounds a sprocket 58 rotatable around a bushing On shaft 59 that is fixed to engine supporting framework 60, framework 60 being fixed to chassis 21. The housing of transmission 26 is of course fixed relative to chassis 21, transmission 26 itself being conventional.

The tractor 20 of the present invention shown in FIGS. 1 and 2 is provided with front and rear caster-type mounted wheels 61 and 62, respectively, and wheels 63 and 64 on opposite sides of the tractor 20 to be driven to move the tractor. As will be apparent, wheels 63 and 64 are driven via sprocket 58 by means of a sprocket 65 fixed to sprocket 58 shown in FIG. 4, and by a chain 66 shown in both FIGS. 3 and 4 that encompasses a sprocket 67 that is fixed to a mechanical differential indicated generaly at 67' in FIG. 5 by means of bolts 68 which hold the parts of the mechanical differential 67 together. Sprocket 67 may be welded, or otherwise fixed, in any convenient manner to one-half of the housing of differential 67' indicated at 69, which is bolted to another half .70 by means of bolts 68. Chassis 21 is slotted at 151 as shown in FIG. 3 and 4 to accommodate sprocket 67 and chain 66 engaged therewith to pass from the position around sprocket 65 above chassis 21 to a position around sprocket 67 below chassis 21. A web 155 is provided approximately at the center of the chassis 21 for strength as shown in FIG. 5. Differential 67' is provided with output shafts 71 and 72, respectively, fixed to wheels 63 and 64, output shafts 71 and 72 being mounted in bearings 73 and 74 respectively, fixed to the chassis 21 by bolts 75 and 76, respectively.

Framework 60, shown in FIGS. 1 and 2, on which the internal combustion engine assembly 22 is mounted is rotatably mounted about a pin 77 held by cotter key 78, pin 77 projecting through a member 79 fixed to chassis 21 by means of bolts indicated at 80 in FIG. 4, the longitudinal position of framework 60 being adjustable by loosening bolts 80 and turning set screws 81 threaded through ears 82 welded to chassis 21 at 83. Bolts 80 can also be seen in FIG. 5. Since framework 60 is rotatable about the pin 77, the horizontal position thereof may be adjusted by means of rotation of a nut 84 which rests on top of a hollow cylindrical body 85 that is pivoted at its lower end about a horizontal axis 86, the hollow passageway inside body 85 being adapted to take the lower threaded end of a shaped rod 87 having an upper end at 88 rotatable in a hole through the framework 60. The gear shift of transmission. 26 is operated by moving. a shaft 89 extending horizontally therein to the right or left, as viewed from the rear of the tractor 20. A movement of shaft 89 is made by rotating pipes 90 or 91 to the forward or to the rear approximately 45°, pipes 90 and 91 being, fixed to end portions 41 and 42, respectively, of the handle bar arrangement which are, in turn, fixed to shaft 43 as shown in FIG. 3. Rotation of shaft 43 rotates an arm 92 that is fixed thereto by means of a set screw 93 to move a rod 94 shown in both FIGS. 1 and 3 approximately vertically upwardly or downwardly, depending upon the direction of rotation of pipes 91 and 92. Pipes 90 and 91 are hollow to permit the . wires 38 and 39, respectively, of cables 32 and 33, to pass downwardly

3,166,141 into the corresponding sheaths thereof, respectively. Rod 94 operates shaft 89 through a lever 95, rod 94 being pivoted at its lower end through a hole through one end of lever 95, a bolt 96 being employed to rotatably mount a block 97 about the other end of lever 95, bolt 96 also holding block 97 in a fixed axial position on shaft 89. A bolt 98 is provided through the comer of lever 95 to maintain it in a position rotatable about bolt 98 on a bracket 99 which is, in turn, bolted at 100 to a projection 101 welded to member 48. This arrangement is shown in both FIGS. 1 and 3.

As shown in FIG. 3, levers 102 and 103 are provided which are maintained in fixed axial positions on shaft 43 although rotatable therearound by means of corresponding set screws 104 and 105, respectively, rotatable in grooves, not shown, in shaft 43. Rotation of levers 102 and 103 independently brake corresponding driven wheels 63 and 64 by operating corresponding brake cables 106 and 197, respectively, shown in FIG. 1.

Another outstanding feature of the invention resides in the use of a universal-type or ball and socket trailer hitch 108 including a ball 199 fixed to a shaft 116 which is threaded into a framework 111 welded to chassis 21. Rotation of shaft 110 is prevented by means of a pin 112 which projects through an appropriate hole in framework 111 and in one of several holes 113 in shaft 110 as shown in FIG. 6. Framework 111 is slotted at 152, as shown in FIGS. 4 and 6, to accommodate sprockets 67 and chain 66.

The socket of the trailer hitch 10S indicated at 114 is incorporated integrally with the forward end of a house trailer indicated at 115, most of which is broken away. House trailer 115 is provided with a conventional jack 116 to lift the socket 114 of trailer hitch 108 above the ball 109 in order that the tractor 20 may be moved rearwardly so that the ball 109 lies immediately below socket 114. In this case, jack 116 can be operated to lower the trailer 115 until the lower end of the jack 116 rises from the ground and socket 114 rests on top of the ball 109.

It will be noted that in accordance with an outstanding feature of the invention, ball 109 is located in a vertical plane through the rotational axis of wheels 63 and 64 midway between them. The same will be appreciated from the views illustrated in FIGS. 3 and 8 when taken together. A construction line 117 has been added in FIG. 8 to illustrate this fact, construction line 117 passing through the center of shaft 110 and through the axis of shaft 72 to which wheel 64 is fixed. From FIG. 5, it will be apparent that both shafts 73 and 72, to which wheels 63 and 64 respectively ’are fixed, have an identical horizontal rotational axis.

Still another outstanding feature of the invention is the use of a U-shaped member 118, perhaps best shown in FIGS. 1, 3 and 6, which is mounted to rotate about bolts 119 which project through ears 120 that are welded to chassis 21. Bolts 119 have a common horizontal axis which must be parallel to the rotational axis of wheels 63 and 64. This orientation can be observed from FIGS. 3, 4, 5, 8 and 10. U-shaped member 118 extends generally in a horizontal plane, although it rotates through relatively small angles with respect thereto about bolts 119 and has a bottom or bight portion at the forward end of the tractor 20 to support chassis 21 thereon through an arrangement perhaps best shown in FIGS. 8 and 9.

Front caster-type wheel 61 is rotatable about an approximately vertical pin 121 that is held in position by a plate 122 welded to the bottom of U-shaped member 118. As shown in FIGS. 1 and 8, front caster-type wheel 61 is not only rotatable about a substantially horizontal axle 141 located through a pair of plates 142 and 143 to which a top plate 144 is welded to provide a fork but also rotatable about pin 121 which is substantially vertical. Plate 145 is bolted to plate 122 by means of bolts 146 shown in both FIGS. 8 and 9. Bolts 146 are also shown in FIG. 5. Between plates 144 and 145, a bushing 147 .

is provided. Plate 122 may be welded to plate 145 if desired, thus, if an end plate portion, indicated at 148 in FIG. 8, is welded to the lower end of pin 121, wheel 61 cannot come loose from, the U-shaped member 118.

A portion of the weight of chassis 21 is actually supported on wheel 61 through threads 123 on a shaft 124 that is rotatable by handle 125. Shaft 124 is threaded . into a square nut 126 supported in the channel of a bracket 127 that is, in turn, welded to members 48 and 49, IO which, it will be recalled, are bolted to chassis 21 at 50 and 51. Nut 126 is rounded at its upper end to permit it to rock in bracket 127. A portion of the weight of chassis 21 is then supported on a helically coiled spring 128 at a plate 129 located on top thereof between the top jg of the spring 128 and a shoulder 130 on shaft 124, plate 129 having a hole 131 therethrough through which an extension 132 of shaft 124 projects and is slidable in a bearing 133 located in a pipe extension 134 that is welded to bracket 135, perhaps -best shown in FIG. 9. A ring 149 20 is also welded to bracket 135 to contain the lower end of spring 128, a set screw 150 being threaded through ring 149 to maintain the lower end of spring 128 in place against bracket 135.

Bracket 335 is rotatable about bolts 136 and 137 which 25 project therethrough and through corresponding ears 138 and -139 welded to U-shaped member 118 and to plate 122 which is also welded thereto. The rocking action of Ushaped member 118 about bolts 136 and 137 is permitted in order that shaft 124 can rotate when U-shaped member 30 US does so.

In : accordance with an outstanding feature of the invention, the operation of the U-shaped member 118 is as illustrated in FIG. 10 wherein shaft 124 is rotated by handle 125 to lift rear caster-type wheel 62 upwardly. 35 This is permitted in accordance with the invention because it is necessary to provide this feature to take the tractor 20 over rough ground. It will be evident from a comparison of FIGS. 8 and 10 that U-shaped member 118 is at a substantially greater angle with respect to the hori40 zontal in FIG. 10 than in FIG. 8.

Rear caster-type wheel 62 is mounted identically with front caster-type wheel 61. As a matter of fact, structures 141, 142, 143, 144, 145 and 146 incorporated in mounting front caster-type wheel 61 may be identical to 45 the structures indicated at 141', 142', 143', 144', 145' and and 146', respectively, illustrated in FIGS. 1 and 10. The same, is true of the identity of structures 121', 147' and 148' to mount rear caster-type wheel 63 as regards structures.121, 147 and 148 employed to mount front caster50 type wheel 61 as shown in FIG. 4. A beam 122' has its forward end fixed to chassis 21 by means of a pair of bolts 76 employed in mounting one of the bearings 74 shown in FIG. 5 thereto. Member 122' serves the same purpose as plate 122 perhaps best shown in FIG. 8 in mount55 ing front caster-type wheel 61? Thus; it is to be noted that not only is the front wheel 61 a caster-type wheel, but also the rear wheel 62.

As shown in FIGS. 5, 6, 7 and 8, right and left brake springs 153 and 154 are employed to bias the brakes of 60 corresponding wheels 63 and 64 to a deactuated position, one end of the springs 153 and 154 being connected to the brakes of corresponding wheels 63 and 64 and the other end of springs 153 and 154 being connected to chassis 21.

A modification of the invention is shown in FIG. 11. The remainder of the tractor, not shown, may be identical to that illustrated in FIGS. 1 to 10, inclusive. Many of the structures shown in FIG. 11 may also be identical to those shown in. FIGS. 1 to 10, inclusive. In the first 70 place, a sprocket 58' is shown which may be identical to sprocket 58 shown in FIG. 2. A pair of driven wheels 63' and 64' are also provided in FIG. 11 which may be identical to wheels 63 and 64, the difference being in the drive to wheels 63' and 64'. The embodiment of the invention shown in FIG. 11 is adapted to take the nose

3,166,141 wheel of the tricycle landing gear airplane in a slot 156 in chassis 21' which may otherwise be identical to chassis 21. A mechanical differential 67, which may be identical to differential 67', is located forward of the rear end of chassis 21'. It is fixed to sprocket 58'. Differential 67 drives output shafts 71' and 72' which, in turn, rotate corresponding sprockets 157 and 158. Sprockets 157 and 158 through chains operate sprockets 159 and 160, respectively, which are fixed to shafts 161 and 162, respectively, connected to driven wheels 63' and 64'. Mechanical differential output shafts 71' and 72' are maintained in a fixed axial, but rotatable, angular position by means of corresponding bearings 163 and 164. The shafts to which wheels 63' and 64' are fixed, that is, shafts 161 and 162, are maintained in fixed axial, but rotatable angular positions in bearings 165 and 166 respectively by means of pins 167 and 168 through shafts 161 and 162, respectively.

Additionally, means are provided on chassis 21' to lift the nose wheel of the airplane off of the ground. This means includes a jack 169, as shown in FIG. 12, which is provided with a handle 170 to rotate a shaft 171 that is threaded through a plate 172 that is hinged to chassis 21 at 173, the hinge including a plate 174 welded to chassis 21. Thus, the lower end of shaft 121 lifts plate 172 from chassis 21. A tubular member 175 is welded to plate 172. Tubular member 175 has inwardly turned ends 176 and 177 at the rearward end of its legs. The nose wheel axle of airplanes conventionally have a hollow internal passageway into which projections 176 and 177 may be fitted by springing legs of U-shaped member 175 apart. Alternatively, screw threaded means, similar to jack 69 may be employed, such means extending transversely through ears fixed to the opposite legs of Ushaped member 175. Such screw threaded means may be employed to adjust the transverse position of ends 176 and 177 until they are spread far enough apart to accommodate the ends of the nose wheel axle and subsequent to be closed into a position internally thereof.

Still another embodiment of the invention is illustrated ⁴⁰in FIGS. 13 and 14. Those portions of the tractor omitted may be identical to that shown in FIGS. 1 to 10, inclusive. The only modification is the mounting of member 122'. A member 122' may be identical to member 122' but for the means for mounting it to a chassis 21 which may be identical to chassis 21. This means includes a pair of ears 178 welded to chassis 21, a pair of ears 179 welded to member 122' and a bolt 180 through each of the four ears 178 and 179 as indicated in both FIGS. 13 and 14. In this manner, member 122' is rotatable , about the bolt 180 with respect to chassis 21, whereby chassis 21 may be rotated upwardly and rearwardly about axle 71 and 72 of wheels 63 and 64, respectively, to place ball 109 of trailer hitch 108 under socket 114 of trailer 115 without the necessity of raising the trailer ; 115 by means of jack 116. The same is useful in handling boat trailers in which tractor 20 of the present invention may be made very small.

The rotatable character of member 122' is indicated in dotted lines at 122 i '* ' ; 2:_ „ vided in FIG. 13 to maintain member 122' in a fixed horizontal position parallel to that of chassis 21 when it is not desired that the tractor of the invention be rotated as explained in the immediately preceding paragraph. . ________________{____}

Hook 181 is rotatable about a pin 182 which extends _C5 member 118, on rough ground, the height of fronfwheel through an ear 183 welded to chassis 21. An angle stop ......

bracket for hook 181 is provided at 184. Hook 181 is biased rearwardly by means of a coil spring 185. Due to the shape of hook 181, the member 122' is stable in either of its hooked or unhooked positions. That is, if ₇₀ . Notwithstanding the fact that the embodiment of the member 122' is maintained in a position shown in solid ’ —.....lines in FIG. 13 by hook 181, the same will not become unhooked due to bias action of spring 185. Still further, the bias action of spring 185 with stop 184 and the parmember 122' from being hooked when it is unhooked as indicated in the dotted lines 122'' shown in FIG. 13.

From the foregoing, it will be appreciated that the primary skid described hereinbefore attendant upon the rotation of two dirigible wheels of a conventional four-wheeled vehicle about vertical axes in planes parallel to each other is completely avoided by the use of front and rear castertype^ wheels 61 and 62 in accordance with the present invention with the pair of wheels 63 and 64 driven by a conventional mechanical differential 67'. However, although primary skid is avoided in accordance with the tractor 20 of the invention, the tendency of the tractor 20 to tip over is effectively eliminated by use of the four wheels 61, 62, 63 and 64, rather than three wheels.

In accordance with another outstanding feature of the present invention, the universal-type, that is, ball and socket trailer hitch 108 is employed. This means that the tractor 20 may be employed to turn from a 90° right turn to a 90° left turn and vice versa without substantial physical effort being involved, and without the need for any mechanical power from the tractor engine in housing 23. This is true because the tractor 20 can be so turned without, in fact, moving house trailer 115 which may be hitched to it. The trailer 115 may, in fact, be hitched to the tractor 20 when the tractor is turned 180°, and still no substantial physical effort is involved in turning the tractor 20 manually. Note will be taken that the mechanical differential 67' in combination with the particular support position of trailer hitch knob 109 on framework 111 fixed to chassis 21 provides this unusual ease in turning advantage, both mechanical differential 67' on the trailer support position of knob 109 directly above the common axis of rotation of driven wheels 63' and 64' in a vertical plane midway between them being indispensable in this one regard. In the same regard, it is to be noted that use of the universal-type trailer hitch 108 is unusually useful when employed with tractor 20 of the present invention where sharp turns are required, and especially on rouah ground.

In turning, when power is supplied to driven wheels 63 and 64, it is also a feature of the invention that each one of the driven wheels 63 and 64 may be braked independently by operation of levers 102 and 103 corresponding respectively thereto. The use of the same further increases ease of steering.

According to an aspect of the invention, the tractor 20 of the invention is unusually useful in employing the combination of chassis 21, caster-type wheels 62, and driven wheels 63 and 64 mounted on each side of the chassis 21. The driven wheels are fixed to shafts 71 and 72 respectively in positions to rotate in respective longitudinal planes. When power means, including the internal combustion engine in housing 23, are employed, including mechanical differential 67' mounted on chassis 21 for 5 rotating driven wheels 63 and 64 and U-shaped member 118 is additional provided having legs extending rearwardly toward driven wheels 63 and 64 in an approximately horizontal plane, the U-shaped member 118 can rotate about its ends and about the axes of bolts 119. in FIG. 13. A hook 181 is pro- go Thus, by suspending front caster-type wheels 61 from the bight or bottom portion of U-shaped member 118 at the front of the tractor 20, and providing means including shaft 124 and nut 126 to support the forward end of chassis 121 movably on the bight portion of U-shaped 61 may be adjusted by rotation of shaft 124 by meansof handle 125 to ride higher than the driven wheels 63 and 64 with rear caster-type wheel 62 and the tractor 20 will thereby ride over large bumps in the road.

5ο invention shown in FIG. 11 is different from that shown in FIGS. 1 to 10, inclusive, in certain respects, it is still to be noted that the forward end of an airplane will be sup_ , ported substantially in a vertical plane through the axes ticular shape of the lower end of hook 181 will prevent ₇₅ of shafts 161 and 162, as indicated at dotted line 186 in

3;166, 9'

FIG. 12. This means that the advantage of the present invention overcoming primary skid and ease in turning is maintained. It is to be noted that the support of a nose wheel of a tricycle landing gear airplane is also “universaltype” trailer hitch and is defined as the same for use here- 5 inbefore and hereinafter, including its specific use in the claims because the nose wheel of the tricycle landing gear airplane is not only rotatable about a horizontal axis, but also about the vertical axis of the strut from which it is suspended. 10

Still another feature of the invention resides in the use of the alternative mounting embodiment of FIGS. 13 and 14 in which member 122' is rotatable about the bolt 180. Bolt 180 is maintained in a fixed position relative to chassis 21, whereby a speedy and efficient connection be- 15 tween trailer hitch knob 109 and socket 114 on a boat trailer may be made. This can be performed by manually unhooking hook 181 from the forward end of member 122', lifting the tractor to make it rotate upwardly and rearwardly at the front thereof about the axes of wheels 63 and 64. The tractor is then moved rearwardly until the ball of the trailer hitch lies directly beneath the socket thereof.

It is well known that the housing of differential 67' may be locked to chassis 21 to provide a parking brake.

Shaft 110 of FIG. 6 may be smooth and hydraulic or electric power means may be employed to move it.

In FIGS. 15 and 16 an alternative embodiment of the invention is illustrated in perspective. The same is unusually useful in connecting a tractor as indicated at 15A to the socket of a ball-and-socket type trailer hitch on a boat trailer. However, the trailer hitch connection may be employed on any type of trailer. Driven wheels of tractor ISA are shown at 15B and 15C. A member 15D is fixed to a chassis 15E of tractor 15A to support a 35 caster-type wheel rearwardly of the chassis 15E. A ball 15F of a ball-and-socket type trailer hitch is mounted on a framework 15G that is rotatable by a bolt 15H that extends through the bottom of framework 15G and through a pair of ears 151 welded to chassis 15E. A handle 151 40 is welded to framework 15G to rotate the same upwardly and rearwardly.

Handle 15J is maintained in a fixed position on top of chassis 15E by means of a hook 15K which has a handle 15L fixed thereto. Hook 15K is rotatable with respect to -³chassis 15E on a pin 15M fixed to chassis 15E. A stop 15S is also fixed to chassis 15E to prevent rotation of hook 15K to the left as viewed in FIG. 15 when handle 151 is rotated to a position as shown in FIG. 16. A spring 158 has one end fixed to chassis 15E and another end fixed ⁵⁰to the lower end of hook 15K to maintain the portion of hook 15K beneath pin 15M against stop 15N. Handle 15J is rotated to the position shown in FIG. 16 by first rotating hook 15K to the right as viewed in FIG. 15 until hook 15K clears handle 151. As best shown in FIG. 16, ⁵⁵a U-shaped channel 15P is welded to chassis 15E at its lower end to support framework 15G immediately below a front portion of a square metal plate 15Q of framework 15G.

Thus in the operation of the embodiment of the inven- ⁶⁰tion shown in FIGS. 15 and 16, framework 15G is rotated to the position shown in FIG. 16 and tractor 15A is moved rearwardly until the socket of a ball-and-socket type trailer hitch lies approximately above ball 15F. Handle 151 is then pushed downwardly to the position shown in FIG. 15 to lift the trailer by engagement of the ball 15F with the socket of the trailer hitch.

From the foregoing, it will be appreciated that although only a few specific embodiments have been shown and described, many changes and modifications will, of course, suggest themselves to those skilled in the art. Hence, the invention is not to be limited to the specific embodiments illustrated, the true scope thereof being defined only in the appended claims.

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