Mowing tractor with towed mower

The towed mower (22) is attached by a hitch (44) to the self propelled front mower (21). The front mower has its own forwardly positioned cutter unit (30). The towed mower has a centrally positioned frame segment (62) that does not include a cutting blade, and the two side frame segments (63) and (64) each include cutting blades that are supported in bat-wing fashion from the central frame segment. The swath cut in the grass by the front mower 21 is straddled by the swaths cut by the blades of the side frame segments (63) and (64) of the towed mower (22).

FIELD OF THE INVENTION 
The invention disclosed herein relates to a self propelled riding mowing 
tractor or mowing machine of the type adapted for cutting grass and other 
vegetation, and includes a towed mower which can be detachably mounted to 
the front self propelled mowing tractor in trailer fashion, and the towed 
mower can be attached to and work in combination with the front mowing 
tractor for cutting over relatively flat, wide terrain, with the mowing 
tractor cutting a central swath in the grass and the towed mower cutting 
outer swaths in the grass that straddle the central swath. 
DESCRIPTION OF THE PRIOR ART 
Self propelled riding mowers are commonly used for the purpose of cutting 
grass and other vegetation and the mowers have been constructed in several 
different design categories. Mowers are commonly used for the purpose of 
cutting grass and other vegetation for agricultural and ornamental 
purposes. Mowers are constructed in different categories such as walk 
behind, riding, and remote controlled. Mowers are pushed, pulled, self 
propelled and self powered, or are powered and propelled by tractors or 
other accommodating units. The cutters on mowers consist of one or more 
cutting devices, such as rotary blades, reel cutters, flail cutters and 
sickle bar cutters, which are grouped into cutter assemblies. Several 
cutter assemblies may be used on one mowing machine. 
For example, the prior art mower designs include the conventional high 
standing farm style tractor, garden tractor or mowing machine having 
cutter elements mounted beneath the belly of the tractor, behind the 
steerable front wheels and in front of the rear powered wheels. 
Another prior art mower assembly includes the conventional farm style 
tractor and a towed mower assembly pulled behind the tractor, with the 
power take off system of the tractor functioning to power the cutter 
elements of the towed mower. In some instances, the towed mower includes a 
central, forwardly positioned rotary cutting blade and side blades 
positioned out to the side and slightly behind the forward blade, with a 
central gear box that is driven by the power take off of the tractor, and 
with driving shafts extending from the central gear box to the side 
cutting blades. In some models the cutting blades are driven by hydraulic 
motors, with the tractor having a pump that operates the hydraulic motors. 
The individual side cutter assemblies on this style of mower usually can 
be tilted to cut at different heights or to reduce the width of the unit 
for better handling, particularly when the mower is in transit on a public 
road. When the side cutter blades are raised with respect to the center 
cutter blades, the center cutter blade does not have shields that prevent 
objects from being thrown to the side. Therefore the mower is unsafe to 
operate with side cutter blades raised. 
Another type of prior art mower comprises a tractor or self propelled mower 
provided with cutter assemblies that are positioned out in front of the 
tractor, or under its belly, and some include both front and side mounted 
cutter assemblies to broaden the swath cut by the assembly. These side 
cutter attachments normally follow the contour of the ground but may be 
raised and lowered to cut over objects or to facilitate transit. 
Another type prior art mower configuration used for slope mowing is the 
type generally illustrated in U.S. Pat. No. 4,700,536 and comprises a low 
profile slope mower which includes a power unit having rear driving wheels 
and a forwardly positioned cutter unit which supports the cutter blades. 
The low profile of this unit together with the relatively high engine 
power and good maneuverability of the unit makes the unit stable when 
cutting on sloped surfaces, such as along the embankments of interstate 
highways, golf course embankments, ditch banks, ski slopes and other 
finish, refined or roughly vegetated sloped terrains. 
However, none of the prior art mowers known to the inventor have 
successfully included a front self propelled riding mowing tractor with 
its own cutter and a rear trailing towed mower connected to the front 
tractor by a central pivoting hitch, with side cutters that straddle and 
broaden the swath cut in the grass by the front mower and which can be 
tilted upwardly. It is to this arrangement of mower elements that this 
invention is directed. 
SUMMARY OF THE INVENTION 
Briefly described, the present invention comprises a front cutting or belly 
cutting self propelled riding mowing tractor or mowing machine, with a 
rear towed mower, whereby the towed mower is pulled along in trailer 
fashion behind the forwardly positioned self propelled mowing tractor. The 
front self propelled mowing tractor or mowing machine, referred to 
sometimes herein as the "front mower", includes its own cutting unit with 
an engine that is used to power its driving wheels as well as its front or 
belly mounted mower. A trailer connecting device is mounted between the 
front mower and the towed mower so that the towed mower is connected to 
and follows the front mower in trailer fashion. 
The towed mower has three frame segments. The central frame segment 
includes ground engaging support wheels, a portion of the connecting 
device to the front mower and hinge means for the two side frame segments. 
The side frame segments each includes at least one cutter and a supporting 
wheel member. The cutters of the towed mower assembly preferably are 
powered by the engine of the front mower; however, the towed mower can be 
constructed with its own independent source of power to its cutters. The 
noncutting central frame segment of the towed mower is positioned so as to 
ride over the swath previously cut by the cutter unit of the front self 
propelled mower, whereas the side segments of the towed mower are 
positioned so that their cutters cut swaths that straddle and intersect 
the central swath, resulting in the formation of one wide uninterrupted 
cut. 
The prior art towed mowers of the type having a center cutter and hinged 
side cutters typically have the cutters arranged in a longitudinally 
staggered, overlapped relationship so as to avoid leaving streaks of uncut 
grass. Because of this requirement these cutter assemblies are long in 
relation to their width. However, the towed mower of this invention has 
its central frame segment constructed without a cutter. Therefore the 
cutters of the side frame segments of the towed mower do not have to be 
offset longitudinally with respect to a central cutter and the length of 
the towed mower of this invention is shortened by the absence of the usual 
central cutter. Moreover, the overall length of the combined self 
propelled front mower and towed mower is shortened. Further, the distance 
between the supporting wheels of the towed mower and the rear driving 
wheels of the forwardly positioned self propelled mower is minimized by 
the short configuration of the towed mower. This configuration results in 
the towed mower closely following the swath cut by the forwardly 
positioned cutter of the self propelled mower when the self propelled 
mower and towed mower are driven through a turn, as well as when trailing 
over undulating turf. When the two cutter units are raised vertically on 
the towed mower the width of the towed mower is less than the width of the 
front mower and the front mower can be used to trim close to and around 
objects since the nonfunctioning towed mower will trail within the cut 
swath of the front mower. This configuration provides the best trimming 
capability of the front mower as the rear mower does not engage an 
obstacle outside the path of the front mower. 
Optionally, the trailer connecting device that connects the towed mower in 
trailer fashion to the front mower can be made easily detachable, enabling 
the operator to quickly attach and detach the towed mower from the self 
propelled front mower, so that the operator can mow the broad, flat 
surfaces of an area with the combination of the self propelled front mower 
and the rear towed mower, and the operator can quickly detach the towed 
mower from the front mower and use the front mower separately to mow in 
confined areas, to perform slope mowing or to power or propel various 
attachments that can be mounted to the front mower. 
Thus, it is an object of this invention to provide an improved self 
propelled front mower and towed mower combination, whereby the towed mower 
is towed behind the front mower in trailer fashion and the cutters of the 
towed mower straddle and broaden the cut swath formed by the cutters of 
the front mower. 
Another object of this invention is to provide a towed mower that is 
adaptable for being towed behind a front self propelled mower, whereby the 
towed mower has laterally displaced side cutting elements which are 
arranged to straddle the swath cut by the forwardly positioned cutter unit 
of the self propelled mower, and includes a central frame segment that 
does not have a cutting element and rides over the swath cut by the 
forwardly positioned self propelled mower and which allows the towed mower 
to be relatively short in length and highly maneuverable. 
Another object of this invention is to provide a towed mower for attachment 
to a front mower which has a central frame segment and vertically hinged 
side frame segments which can be raised to nonoperating vertical positions 
for transport and to facilitate trimming with the front mower and to avoid 
collision between the rear mower and obstacles being trimmed around. 
Another object of this invention is to provide a self propelled mower with 
a detachable towed mower, with the front self propelled mower being of low 
center of gravity construction suitable for mowing on sloped surfaces, and 
with the rear towed mower comprising three frame segments which are 
tiltable with respect to each other, with a central frame segment arranged 
to ride over the swath cut by the front self propelled mower and with the 
side frame segments supporting cutters that cut side swaths that straddle 
and broaden the central swath cut by the front mower. 
Another object of this invention is to provide an improved, light weight 
towed mower that closely follows a front mower in centrally pivoted 
trailer fashion and which includes side cutters that straddle and broaden 
the swath cut by the front mower, and which skew to the side when 
propelled into objects that may have passed to the side of the front 
cutter so that damage to the towed cutter, dislocation of the front mower 
and damage to the object impacted are all reduced or substantially 
eliminated because of the angled arrangement of the cutters along with 
angled front edges of the housing and the relatively reduced weight and 
length of the towed mower due to the absence of a center cutting section. 
Another object of this invention is to provide a self propelled front mower 
with a centrally pivoted detachable towed mower giving a combined wide 
cutting swath and a short turning radius due to the overall length of the 
towed mower being reduced by the absence of a center mowing section. 
Another object of this invention is to provide a front self propelled mower 
and a rear towed mower combination with the towed mower having cutter 
sections that straddle the cut swath formed by the front mower and which 
can be tilted to upright inoperative positions as the front mower 
continues to operate and continues to form its cut swath. 
Another object of the invention is to provide a self propelled front mower 
and a towed mower combination, with the towed mower having side cutters 
that straddle the swath cut by the front mower and which can be tilted 
upwardly to inoperative positions so that the width of the towed mower is 
less than the width of the front mower whereby the front mower can be used 
to trim about objects with the towed mower trailing directly in the cut 
swath of the front mower in a path that will not impact the objects 
trimmed around by the front mower. 
Other objects, features and advantages of this invention will become 
apparent upon reading the following specification, when taken in 
conjunction with the accompanying drawings.

DETAILED DESCRIPTION 
Referring now in more detail to the drawings, in which like numerals 
indicate the like parts throughout the several views, FIG. 1 illustrates 
the mower assembly 20 which includes a front self propelled riding mowing 
tractor 21 and a rear towed mower 22. The front self propelled mowing 
tractor 21, referred to as the "front mower", is illustrated as a slope 
mower of the type that has rear powered driving wheels 24 and 25, front 
steerable wheels 26 and 27, with the rear powered wheels 24 and 25 
supporting a power unit 29 and the front steerable wheels supporting a 
cutter unit 30. 
The power unit 29 of the front mower 21 includes an internal combustion 
engine 31 that operates a plurality of pumps 32, 33 and 34 which are 
mounted in series on the engine 31. Pump 32 is the wheel propulsion pump, 
pump 33 is the front deck drive pump, and pump 34 is the drive for 
auxiliary functions such as power steering and lift cylinders. Other pumps 
(not shown) are located behind and are driven by the engine which function 
as the towed mower drive pumps. 
A pivot connection 36 functions to connect the cutter unit 30 to the power 
unit 29 so that the cutter unit 30 is pivotable about a longitudinal axis 
38. The pumps 32-34 project from the internal combustion engine 31 over 
the pivot connection. With this arrangement, the cutter unit 30 can tilt 
with respect to the power unit 29 during the movement of the mower 
assembly over uneven terrain, and the pumps 32, 33 and 34 remain in a 
space above the cutter unit 30 without obstructing the tilting movements 
of the cutter unit with respect to the power unit. 
The power unit 29 includes a driver's seat 40 that is located rearwardly of 
the driving wheels 24 and 25, with a steering wheel 41 and various 
throttle controls, pump controls and other controls 42 located in front of 
the driver's seat. A trailer tongue 44 projects from the power unit 29 
adjacent the driving wheels 24 and 25 rearwardly beneath the driver's seat 
to the towed mower 22 and is connected to the towed mower. 
The cutter unit 30 of the front mower 21 has a hydraulic motor 45 mounted 
to the decking of the cutter unit, and a drive sheave 46 mounted on top of 
the motor 45 engages the driving belt 48. The driving belt 48 extends to 
driven sheaves 49, 50 and 51 and the sheaves are each connected by means 
of a mandrel to a cutting blade beneath the decking of the cutter unit 30. 
A spring biased idler sheave 52 maintains proper tension in the driving 
belt 48. The rotary cutters 53a, 53b and 53c driven by the driving belt 48 
are arranged in a triangular staggered relationship with respect to each 
other so as to cut a single swath in the grass beneath the cutting deck 
21, as indicated by the dash lines 54 and 55. 
The front self propelled mower 21 is steered by its front steerable wheels 
26 and 27. Hydraulic cylinders 56 and 57 impart steering motion to the 
wheels 26 and 27, and the cylinders 56 and 57 are operated by a power 
steering pump 34, which is in turn controlled by the steering wheel 41 of 
the power unit 29. Fuel tanks 59 and 60 are mounted to the decking of the 
cutter unit 30 and supply fuel to the internal combustion engine 31. 
As illustrated in FIG. 2, the rear towed mower 22 comprises a support frame 
61 having a central segment 62 and side segments 63 and 64 located on 
opposite sides of the central segment 62. The side segments 63 and 64 are 
covered by sheet metal decking, with the decking forming part of the side 
segment support frame. The side segments 63 and 64 are tiltable with 
respect to the central segment by means of hinges 66, 57 and 68, 69. 
Hydraulic cylinders 70 and 71 are each connected between a central frame 
element 72 on the central segment 62 and to stanchions 73, 74 mounted to 
the side segments 63, 64. When the cylinders 70 and 71 are retracted, the 
side segments 63 and 64 are tilted up to a vertical attitude suitable for 
highway travel, and when the cylinders 70, 71 are extended the side 
segments 73 and 74 are tilted back down to a horizontal attitude suitable 
for mowing. 
Central support wheels 75 and 76 are positioned behind and slightly out to 
the side of central segment 62 of the rear towed mower 22 with the wheels 
being mounted to axle 78. The axle in turn is mounted to support arms 79 
and 80, with the support arms being pivotably mounted at their forward end 
portions to stanchions 81 and 82 of central segment 62. Hydraulic 
cylinders 83 and 84 extend between central frame element 72 in a 
downwardly sloped direction and each cylinder 83, 84 is connected at its 
lower end to support arm 79 or 80. When the cylinders 83 and 84 are 
extended, the rear portion of the support frame 61 is raised away from the 
ground surface by the downward tilting of the support arms 79 and 80. 
Likewise, when the cylinders 83 and 84 are retracted, the support arms 79 
and 80 tend to assume a horizontal attitude, thereby lowering the rear 
portion of the support frame 61. This permits the operator to selectively 
elevate the rear portion of the support frame of the central segment 62. 
As illustrated in FIGS. 2 and 3, the trailer tongue assembly 44 which 
connects the front self propelled mower 21 to the rear towed mower 22 
comprises an approximately U-shaped forward tongue member 86 having side 
legs 87 and 88, a base leg 89 and coverging legs 90 and 91. The distal 
ends of the side legs 87 and 88 have laterally extending pins 93 and 94 
rigidly mounted thereto, and the pins 93 and 94 are pivot about axis 97 
and are releasibly received in sockets 95 connected to the frame of the 
front self propelled mower 21 immediately adjacent the axis of rotation of 
the rear powered wheels 24 and 25. The connection of the forward tongue 
member 86 to the frame of the front self propelled mower immediately 
adjacent the driving wheels 24 and 25 causes the weight of the rear towed 
mower 22 that is applied to the front self propelled mower 21 to be 
applied adjacent the wheels 24 and 25, thereby minimizing any tilting 
effect of the applied weight to the front mower. When the towed mover is 
to be detached from the front mower the pins 93 and 94 are withdrawn from 
the sockets 95. 
The trailer tongue assembly 44 further includes a universal joint 96 (FIG. 
3), which includes a double clevis connector 98 and a swivel assembly 99. 
Double clevis connector 98 includes a base plate 100 and forwardly 
extending vertical clevis leaves 101 and 102 and rearwardly extending 
horizontal clevis leaves 103 and 104. A socket 105 is mounted in a 
horizontal attitude to the rear portion of forward tongue member 86, and 
pivot pin 106 extends through socket 105 and aligned openings of the 
forwardly extending vertical clevis leaves 101 and 102. This forms a 
horizontal pivot connection between the double clevis connector 98 and 
forward hitch member 86 about the horizontally extending axis 108. 
Swivel assembly 99 includes a pair of spaced parallel support bars 110 and 
111, with a vertical socket 112 mounted between the bars 110 and 111 at 
their forward end portions. The socket 112 is oriented vertically and is 
positioned between aligned openings of the rearwardly extending horizontal 
clevis leaves 103 and 104, and pivot pin 113 extends through the socket 
112 and the openings of the clevis leaves 103 and 104, forming a vertical 
pivot axis 114. 
The rear end portions of support bars 110 and 111 of the universal joint 96 
are rigidly connected together by means of plates 116 and 117, and the 
plates 116 and 117 together with the support bars 110 and 111 surround 
lateral frame element 118, angle frame legs 119 and 120 and base leg 121. 
Pivot pin 122 extends through lateral frame element 118 and base leg 121, 
and through plates 116 and 117. The support bars 110 and 111 are spaced 
apart a distance greater than the thickness of the lateral frame element 
118 and base leg 121, so that these elements can tilt with respect to each 
other around pivot pin 122. This construction permits the U-shaped forward 
tongue member 86 to rotate about the longitudinal axis 123 with respect to 
the support frame 61, with the longitudinal axis 123 extending along the 
length of the pivot pin 122. Thus, the universal joint 96 allows the rear 
towed mower 22 to have freedom of movement around the two axes 114 and 123 
while the hitch pins 93 and 94 and their sockets 95 permit freedom of 
movement about axis 97 as the rear towed mower 22 is pulled by the front 
self propelled mower 21 over uneven terrain. 
The height of the forward portion of the support frame 61 is adjustable by 
means of hydraulic cylinder 124. The end portions of cylinder 124 are 
connected to the stanchions 125a and 125b, with the retraction of the 
cylinder rod into the cylinder causing the stanchions 125a and 125b to 
move closer together and therefore move the trailer tongue 44 down toward 
the ground and thereby moving the forward portion of the support frame 61 
downwardly, whereas when the cylinder rod of cylinder 124 is extended, the 
stanchions 125a and 125b are urged apart so as to tend to lift the trailer 
hitch away from the ground and to raise the forward portion of support 
frame 61. 
With this arrangement, when cylinders 83, 84 and 124 are extended, the 
support frame 61 of the rear towed mower will be lifted away from the 
ground surface. Likewise, when the cylinder 83, 84 and 124 are retracted, 
the support frame 61 will be lowered toward the ground. 
As illustrated in FIGS. 1 and 2, side segments 63 and 64 of the support 
frame 61 of rear towed mower 22 are supported by caster wheels 126 and 
127, with the caster wheels each having a support arm 128 extending from 
the stem 129 of each caster wheel laterally over to the decking of the 
side segment 63 or 64 of the rear towed mower 22. With this arrangement, 
the outer side portions of the side segments 63 and 64 of the support 
frame 61 are supported by the caster wheels 126 and 127, so that the side 
segments can undulate or pivot with respect to the central segment 62 in 
bat-wing fashion. 
Each side segment 63 and 64 includes a hydraulic motor 130 that drives a 
sheave 131, with the sheave powering the driving belt 132. The driving 
belt 132 extends about the cutter blade sheaves 134 and 135, with one or 
more spring urged idler sheaves 136 and 137 applying tension to the 
driving belt 132. The cutter sheaves 134 and 135 each are mounted to a 
mandrel that is connected to a cutting blade 138a and 138b, respectively, 
beneath the decking of the side segments 63 and 64, so that the driving 
belt 132 rotates the cutting blades at high angular velocities so as to 
cause the cutting blades to cut the grass or other vegetation immediately 
beneath the side segments 63 and 64. 
The embodiment of the towed cutter illustrated in FIGS. 1-3 includes two 
rotary cutting blades 138a and 138b positioned in each side segment 63 and 
64 of the support frame 61 of the rear towed mower 22, with the cutting 
blades sloped rearwardly on opposite sides of the mower assembly so that 
they slightly overlap with respect to each other as the mower assembly 
moves in a forward direction as indicated by direction arrow 140. The 
overlapping cutting blades therefore cut a continuous swath in the grass 
as indicated by dash lines 141 and 142, and 143, 144, respectively. The 
swath lines 142 and 143 are positioned so as to overlap the swath cut by 
the front mower 21, as indicated by swath lines 54 and 55. 
As illustrated in FIG. 1, the forward edge portions or skirts 146 of the 
decking of the cutter unit 30 of the front mower 21 curve about the paths 
of the outer end portions of the cutting blades 53a and 53b. The front 
skirts 148 of the side segments 63 and 64 of the rear towed mower 22 are 
sloped rearwardly and outwardly. This slanted arrangement provides a 
fender effect for the towed mower, in that if the fender 148 of either 
side segment 63 or 64 should engage an obstruction the fender tends to 
either push the obstruction out of the path of the towed mower, or if the 
obstruction is immovable, the fender engages the obstruction and urges the 
towed mower laterally and guides the towed mower around the obstruction. 
The towed mower tends to skew laterally about its trailer tongue vertical 
axis 114 when encountering the immovable object, and the relatively light 
weight of the towed mower, together with the caster wheels 126 and 127, 
tend to permit this skewing movement. The wheels 75 and 76 tend to skid 
laterally during this movement. 
Bumpers 149 are mounted to the decking to provide additional protection for 
the front skirts 148 when the side segments are raised to upright 
positions. Likewise, bumpers 77 extend from the support arms 79 in front 
of wheels 76 to protect the wheels from obstructions. In the preferred 
embodiment, the outside width of the towed mower with the vertically 
hinged side frame segments pivoted up to vertical nonoperating positions 
is less than the outside width of the front mower so that the towed mower 
will avoid collision with objects trimmed around with the front mower. 
FIG. 4 illustrates another embodiment of the towed mower 150, in which 
three rotary cutting blades, 151, 152 and 153 are mounted in each side 
segment 155, 156. The blades 151-153 in each side segment are angled 
rearwardly in bat-wing fashion so that the blades slightly overlap one 
another in the forward direction of movement to avoid streaks of uncut 
grass being left in the swath of cut grass. 
FIG. 5 illustrates another embodiment 160 of the towed mower, whereby a 
single cutting blade 161 is mounted in each side segment 162, 163 of the 
towed mower. 
FIG. 6 illustrates yet another embodiment of the towed mower whereby the 
towed mower 170 has three cutting blades 171, 172 and 173 arranged in 
triangular relationship in each side segment 175, 176. 
FIG. 7 discloses another embodiment of the towed mower 180 which includes 
side segments 181 and 182 constructed in a manner similar to that 
illustrated in FIGS. 1-3, but a central segment 183 that has its central 
support wheels 185 and 186 located beneath the central segment of the 
support frame. The location of the wheels 185 and 186 in this manner tends 
to cause more of the weight of the towed mower to be supported on its 
wheels rather than on its trailer hitch. 
While the prior art towed mowers require the operator to look back to view 
the operation of the towed mowers when trimming about obstacles, this 
invention utilizes the front mower for trimming. One or both of the two 
side segments 63 and 64 are raised to their vertical nonfunctioning 
positions where they are located inside the swath cut by the front cutter 
and are out of the way of the obstacle being trimmed around. This allows 
the operator to cut with the front mower adjacent an obstacle without 
having to worry about a rear mower impacting the obstacle and permits the 
operator to observe the trimming operation while still looking in the 
direction of movement of the mower. 
As illustrated in FIG. 8, the trailer hitch 190 can be substituted for the 
trailer hitch of FIG. 3 if the forward hitch member 191 is rigidly, not 
pivotally, attached to the front mower. The ball 192 is mounted to the 
forward hitch member 191, and the socket 193 is mounted to the support 
frame 194 of the towed mower. The socket 193 simply receives and rests on 
the ball 192 in the conventional trailer hitch manner. 
As illustrated in FIG. 9, another trailer hitch connection can be formed 
between the front mower and the towed mower, by mounting a caster wheel 
198 to the forward portion of the support frame 199 of the towed mower so 
that the front portion of the towed mower is supported by the caster wheel 
198 and the towed mower remains in a fixed attitude and is 
self-supporting. The U-shaped forward hitch member 200 has the distal ends 
of its arms pivotally connected in clevises 201 and 202, and a socket 203 
is mounted to the forward hitch member 200 so as to receive and rest upon 
the ball 204 of the towed cutter. 
FIG. 10 illustrates another trailer hitch construction which includes a 
caster wheel 206 that supports the forward portion of the towed mower, a 
rigid forward hitch member 207 is mounted to the rear of the front mower 
and supports the ball 208, and the rear hitch member 209 is pivotally 
connected in clevises 210 and 211 to the central segment 212 of the towed 
mower. The socket 214 is mounted to rear hitch member 209 and receives 
ball 208. 
FIG. 11 illustrates another trailer hitch construction which includes a 
caster wheel 220 mounted to tongue 221 that supports the forward portion 
of the towed mower, a U-shaped forward hitch member 222 pivotally 
connected in clevises 223 and 224 about horizontal axis 225 to the front 
mower (not shown) and universal joint 226 extending between the front 
mower and the towed mower. The universal joint includes first connector 
228 which extends through U-shaped hitch member 222 and is connected 
thereto by a washer 229 and bolt 230 so that the first connector is 
pivotable about longitudinal axis 131. The rear end portion of first 
connector 228 comprises a clevis 232. The forward end portion of tongue 
221 also comprises a clevis 234, and intermediate link 235 is connected at 
its ends to the clevises. The clevises and their pivot pins 236 and 237 
are oriented at 90.degree. angles with respect to each other and link 235 
is pivotable about vertical axis 240 and horizontal axis 241. 
FIG. 12 is a schematic plan view of the mower and shows how the mower 
assembly 20 performs when moving through a right hand turn. The rotary 
cutters of the cutter unit 30 of the front mower 21 cut a swath as 
indicated by the right and left swath cuts 54 and 55. In the meantime, the 
towed cutter 22 cuts swaths that straddle and slightly overlap the swath 
54, 55, as indicated by the swath cut lines 141, 142 and 143, 144. The 
distance (H.sub.1) of the vertical axis 114 of the trailer tongue 44 to 
the rear driving wheels 24 and 25 of the front mower as compared to the 
distance (H.sub.2) from the vertical axis 114 of the trailer tongue to the 
central support wheels 75, 76 is constructed so that the towed mower 
always cuts its swath in straddling, overlapped relationship with the 
swath cut by the front mower even when the mower assembly moves through a 
sharp turn in which the front mower is angled up to 60.degree. with 
respect to the towed mower. These distances are indicated on FIG. 13 by 
the designations H.sub.1 and H.sub.2. 
The following formulas show the dimensional relationship between the front 
mower and towed mower necessary to eliminate streaking in which: 
H.sub.1 =distance between vertical axis 114 and the axis of rotation of 
rear driving wheels of front mower 21 
H.sub.2 =distance between vertical axis 114 and the axis of rotation of 
central support wheels of rear towed cutter 22 
WB=Wheelbase=H.sub.1 +H.sub.2 
AA=Articulation Angle 
EQU H.sub.2 =WB-H.sub.1 
##EQU1## 
EQU H.sub.1 =H.sub.1 cos AA+WB-[R.phi..phi.+H.sub.2 tanAA] [cos 
AA.times.cos(90.degree.-AA)] 
Where R.phi. and R.phi..phi. are such that R.sub.3 -R.sub.1 =R.sub.2 
-R.sub.4 where R.sub.1 is the radius from the turning center of the mower 
to the inside edge 55 of the swath of the cutter unit 30, R.sub.2 is the 
radius from the center to the outside edge 54 of that swath, R.sub.3 is 
the radius from the center to the swath cut line 142, R.sup.4 is the 
radius from the center to the swath cut line 143, 
##EQU2## 
The formula describes in mathematic terms the relationship of the 
dimensions of the front and rear mower that must be maintained to 
accomplish tracking where the rear swaths will coincide with the front 
swath. The actual relationship between these components can be deviated 
from so long as the designed overlap in cutting swaths are adequate to 
compensate for these deviations. The cutting swaths of the rear cutters 
must always overlap the cutting swath of the front cutter so as to 
compensate for errors in the rear mower tracking behind the front mower. 
For example, when the mower assembly is operating on a sloped surface the 
towed mower tends to skid sideways down the sloped surface. Also when the 
mower assembly is driven at a fast pace through a turn the rear mower is 
urged by centrifugal force outwardly of the turn. Also there may be 
intentional and unintentional manufacturing deviations from the formula 
which cause the towed mower to incorrectly track behind the front mower. 
The invention has been disclosed with the internal combustion engine 31 and 
pumps 32, 33 and 34 serving as power means for operating the hydraulic 
motor 45, power steering cylinders, hydraulic cylinders 70, 71, 83, 84 and 
124. Additional pumps can be mounted to the cluster of pumps 32-34, if 
desired so as to provide more sources of power, as may be desired. The 
hydraulic conduits which extend from the pumps to the motors and cylinders 
have not been shown to simplify the drawings. However, it will be 
understood by those skilled in the art that other power units can be 
utilized, if desired. For example, a separate internal combustion engine 
can be mounted to the towed mower unit and can provide the power for the 
cutters of the side segments. Further, when the towed mower is used behind 
the type of power unit that includes a mechanical power take-off system, a 
conventional gearbox and shafts extending from the gearbox out to the 
cutting blades of each side frame segment can be used. 
Further, the front mower can comprise the type of mower that includes a 
support frame with one or more cutters suspended from the frame. 
The cutters illustrated and described herein comprise rotary cutting 
blades; however, other type cutters can be used, if desired, such as reel, 
sickle and flail cutters. 
It should be understood that the embodiments of the invention disclosed 
herein illustrate principles of the invention in a preferred form. Other 
modifications, additions and deletions may be made thereto without 
departure from the spirit and scope of the invention as set forth in the 
following claims.