Vibration damping device and a method for a road planer and the like

A vibration damper for a road planer and the like with a main frame and a sub-frame movably connected thereto. A prime mover and a tool are mounted on the sub-frame, which includes frame members forming compartments adapted to receive lead shot particles therein. The particles absorb vibrational energy from the prime mover and the tool. A method of damping vibration is disclosed wherein vibrational energy is transmitted to the lead shot particles which vibrate and generate heat. The heat is dissipated through the frame members to the atmosphere.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates generally to vibration damping and, in particular, 
to a vibration damper for pavement working equipment. 
2. Description of the Prior Art 
Various types of equipment generate vibration which must be isolated or 
damped for optimum performance. For example, pavement working equipment 
such as planers, grinders, saws and the like generate and are subjected to 
relatively severe vibrational forces which, if left undamped, would 
seriously impair their performance. A typical piece of pavement working 
equipment includes a tool such as a saw, grinder or the like operably 
connected to a prime mover adapted for powering the tool and possibly for 
driving the piece of equipment. 
For example, a ROAD SURFACING APATUS is shown in the commonly-assigned 
Arnswald U.S. Pat. Nos. 4,333,685 and 4,333,686. The Arnswald road planers 
include cutter heads with circular, diamond-tipped saw blades mounted on a 
sub-frame which, in turn, is pivotally connected to a main frame. A prime 
mover comprising an internal combustion engine is also mounted on the 
sub-frame and provides balast for urging the cutter head into contact with 
a pavement surface. The engine drives the cutter head and the 
hydraulically-driven wheels of the planer. 
The sub-frame of the Arnswald planer is subjected to vibration from both 
the engine and the cutter head, both of which are mounted thereon. The 
internal combustion engine produces primarily vibration in a vertical mode 
due to the reciprocation of its pistons. The cutter head, on the other 
hand, produces vibration with respect to the vertical, horizontal (along 
the direction of travel) and axial (transverse to the direction of travel) 
spatial axes. The vibration of the cutter head substantially reduces its 
effectiveness and greatly increases wear on the cutter blades. 
The use of small metal particles for shock and vibration absorption has 
heretofore been proposed. For example, the Hovas U.S. Pat. No. 1,294,467 
discloses a shock absorber with a cylindrical container filled with small 
metal balls which interact with disks mounted on a plunger rod 
reciprocated within the container. The Brown U.S. Pat. No. 2,417,347 
discloses a vibration damper including compartments filled with metal 
particles ranging in size from shot to fine powder, depending upon the 
frequency of vibration to be absorbed. 
However, heretofore there has not been available either a vibration damping 
device or method for a road planer and the like with the advantages and 
features of the present invention. 
SUMMARY OF THE INVENTION 
In the practice of the present invention, a vibration damper is provided 
for a road planer and the like. The road planer includes a main frame and 
a sub-frame pivotally connected thereto. A prime mover and a tool are 
mounted on the sub-frame and subject the latter to relatively severe 
vibration, which impairs the operation of the tool. The sub-frame includes 
a plurality of tubes each enclosing a bore. The bores are substantially 
filled with lead shot particles which are free to move and vibrate with 
respect to each other and the tubes and thus absorb vibrational energy 
from the prime mover and the tool. 
A method of damping vibration is also disclosed which includes the steps of 
providing a frame member with an enclosure, placing lead shot particles in 
the enclosure, vibrating the frame with a prime mover and a tool, causing 
the particles to vibrate with respect to each other and with respect to 
the frame member, converting the vibrational energy of the particles at 
least partly to heat energy and dissipating the heat energy through the 
frame member. 
OBJECTS OF THE INVENTION 
The principal objects of the present invention are: to provide a vibration 
damper; to provide such a damper which is particularly well adapted for 
use with a road planer; to provide such a damper which utilizes hollow 
frame members filled with particles for vibration damping; to provide such 
a damper which is adapted for use with a frame having a prime mover and a 
tool mounted thereon; to provide such a damper which utilizes random-sized 
lead shot as a slightly constrained mass for absorbing vibration; to 
provide such a damper wherein at least some of the shot particles are 
elliptical in configuration; to provide such a damper wherein at least 
some of the shot particles are spherical in configuration; to provide such 
a damper which increases blade life on pavement working equipment; to 
provide such a damper which allows pavement working equipment to operate 
at greater speeds than similar equipment undamped; to provide such a 
damper which is adapted for use on a variety of equipment; to provide such 
a damper which is adapted for use with equipment for working existing and 
new pavement; to provide such a damper wherein the particles also function 
as ballast to provide such a damper which is effective for controlling 
vibration in vertical, horizontal and axial spatial axes; to provide such 
a damper which is economical in operation, efficient to manufacture, 
capable of a long operating life and particularly well adapted for the 
proposed usage thereof; to provide a method of damping vibration; to 
provide such a method wherein undesirable vibration is absorbed by 
particles; to provide such a method wherein vibrational energy in the 
particles is converted to thermal energy; to provide such a method wherein 
the thermal energy is dissipated; and to provide such a method which is 
particularly well adapted for use in conjunction with pavement working 
equipment and the like. 
Other objects and advantages of this invention will become apparent from 
the following description taken in conjunction with the accompanying 
drawings wherein are set forth, by way of illustration and example, 
certain embodiments of this invention. 
The drawings constitute a part of this specification and include exemplary 
embodiments of the present invention and illustrate various objects and 
features thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
As required, detailed embodiments of the present invention are disclosed 
herein; however, it is to be understood that the disclosed embodiments are 
merely exemplary of the invention which may be embodied in various forms. 
Therefore, specific structural and functional details disclosed herein are 
not to be interpreted as limiting, but merely as a basis for the claims 
and as a representative basis for teaching one skilled in the art to 
variously employ the present invention in virtually any appropriately 
detailed structure. 
Referring to the drawings in more detail, the reference numeral 1 generally 
designates a road planer embodying the present invention. The road planer 
1 is of the type disclosed in U.S. Pat. No. 4,333,685 for ROAD SURFACING 
APATUS and U.S. Pat. No. 4,333,686 for ROAD PLANER DEVICE WITH 
AUXILIARY OUTRIGGER DEPTH CONTROL WHEELS, both of which are commonly 
assigned herewith and are incorporated herein by reference. 
I. ROAD PLANER DESCRIPTION 
The road planer 1 generally includes a rigid main frame 2 and a rigid 
sub-frame 3 pivotally connected to the main frame 2. The main frame 2 
primarily comprises a pair of right and left side members 11, 12 extending 
substantially parallel to each other and joined at their respective front 
and back ends 13, 14. Each side member 11, 12 includes front, intermediate 
and back horizontal sections 15, 16, and 17. The intermediate section 16 
is joined to the front and back sections 15, 16 by a rearwardly and 
upwardly sloping leg 18 and by a vertical leg 19 respectively. The side 
members 11, 12 preferably comprise hollow steel tubes with rectangular 
cross-sectional configurations. 
A pair of front wheels 25 are mounted in tandem on the main frame front end 
13 and are coupled to a steering mechanism 26. A rear wheel assembly 29 
comprises two pair of wheels 30, each pair being mounted in tandem 
relationship on a pivotable rear wheel beam 31 which is attached to the 
main frame 2. The front and rear wheels 25, 30 are driven by an hydraulic 
drive, system 32. 
The planer 1 includes a pair of operator's stations each having a 
respective seat 37 and dual controls to facilitate making pavement cuts on 
either the right-hand or left-hand side of the planer 1. The operator's 
seats 37 and a warning beacon 38 are mounted on a pedestal 39 behind the 
side member vertical legs 19. A cutter head cooling and slurry disposal 
system 41 includes an auxiliary engine 42 mounted behind the pedestal 39 
for powering a vacuum pump (not shown) connected to a cyclo-separator 43 
and a water pump (not shown). Water for cooling is supplied to the planer 
1 from a suitable tank vehicle (not shown) through a coupling 44. The 
auxiliary engine 42 may comprise, for example, a Perkins Model No. 4.154 
4-cylinder water cooled diesel engine. 
The sub-frame 3 generally comprises an engine section 51 in front and a 
tool section 52 in back. The engine section 51 includes a pair of right 
and left side tubes 56, 57 extending longitudinally in parallel 
relationship to the direction of travel of the road planer 1. A front 
crosstube 58 interconnects the side tubes 56, 57 at their respective front 
ends. An intermediate crosstube 59 extends between and interconnects the 
side tubes 56, 57 behind the front crosstube 58. Right and left engine 
mounts 61, 62 are attached to the engine section side tubes 56, 57 
respectively at their front ends. A scavenging pump mount 63 is attached 
to the right engine mount 61 and projects upwardly therefrom. 
The sub-frame 3 is pivotally connected to the main frame 2 by a sub-frame 
bearing assembly 66 attached to the front crosspiece 58 by a bearing mount 
plate 67. A transversely extending pivot pin 68 is journalled in the 
bearing assembly 66 and is received in respective ears (not shown) 
extending rearwardly from a crosstube (also not shown) of the main frame 
2. 
The sub-frame tool section 52 includes right and left side tubes 73, 74 
extending in parallel, spaced relation longitudinally in the direction of 
travel. Front and back crosstubes 75, 76 extend transversely between and 
interconnect the side tubes 73, 74. The tool section side tubes 73, 74 are 
spaced farther apart transversely than the engine section side tubes 56, 
57. The engine section side tubes 56, 57 are fixedly attached at their 
back ends to the front crosstube 75 of the sub-frame tool section 52. 
A crossbar 77 extends transversely between the engine section side tubes 
73, 74 parallel to and in spaced relation rearwardly from the front 
crosstube 75. The crossbar 77 preferably comprises solid steel having 
cross-sectional dimensions of, for example, four inches thick and eight 
inches high. 
A pair of outer depth control carrier plates 80 are connected to and extend 
parallel to the side tubes 73, 74. A pair of inner depth control carrier 
plates 85 extend between the crossbar 77 and the back crosstube 76 in 
parallel relation to the side tubes 73, 74 and in spaced relation inwardly 
from the outer depth control carrier plates 80. A rear ballast compartment 
panel 88 extends transversely between the depth control carrier plates 80, 
85. 
The sub-frame tool section 52 defines front and rear ballast compartments 
91, 92. A lower panel (not shown) extends longitudinally between the front 
crosstube 75 and the crossbar 77 and transversely between the side tubes 
73, 74. A front upper panel 95 likewise extends longitudinally between the 
front crosstube 75 and the crossbar 77 and transversely between the side 
tubes 73, 74 whereby the front ballast compartment 91 is completely 
enclosed. 
The rear ballast compartment 92 is completely enclosed in a similar manner 
by a rear lower panel (not shown) and a rear upper panel 96, each of which 
extends, longitudinally between the crossbar 77 and the rear ballast 
compartment panel 88 and transversely between the outer depth control 
carrier plates 80. 
A pair of outrigger wheel assemblies 101 are mounted on the side tubes 73, 
74 at their front ends. A pair of engine mounts 102 are attached to and 
extend upwardly from the front crosstube 75. An internal combustion engine 
or prime mover 103 is mounted on the front and rear engine mounts 61, 102. 
The engine 103 may comprise, for example, a Caterpillar MOD 3406DT 
6-cylinder diesel engine developing 402 horsepower at 2100 revolutions per 
minute. Of course, any suitable power source could be substituted for the 
diesel internal combustion engine 103 disclosed herein. 
A pair of lower cylinder mounts 106 are attached to and project upwardly 
from the crossbar 77. A pair of double-acting hydraulic ram cylinders 107 
are attached to the lower cylinder mounts 106 and to the main frame 2. 
A pair of cutter head mounting brackets 111 are attached to and depend 
downwardly from the side tubes 73, 74 approximately where the latter are 
attached to the crossbar 77. A respective cutter head bearing assembly 112 
is attached to each mounting bracket 111 in downwardly-depending 
relationship therefrom. Each bearing assembly 112 includes a bearing race 
113 and a retainer 114 mounted thereover. The cutter head bearing 
assemblies 112 preferably comprise Dodge special duty double taper roller 
bearings. 
A cutter head 117 includes a shaft 118 journalled in the bearing assemblies 
112 and a plurality of juxtaposed, circular blades 119 mounted on the 
shaft 118 in coaxial relationship with the rotational axis of the cutter 
head 117. The blades may comprise, for example, 14" diameter, 1/8 inch 
thick diamond blades of the type available from the Target Products 
Division of Federal-Mogul Corporation, Kansas City Mo. A standard cutter 
head such as that shown at 117 might include, for example, 174 of the 
blades 119 separated by 0.120 inches thick spacers 120. Cutter head 
pulleys 121 are attached to each end of the cutter head shaft 118. The 
engine 103 is coupled to a right angle drive 124 which includes pulleys 
(not shown) connected to the cutter head pulleys 121 by multiple drive 
belts (also not shown). The engine 103 is also connected to an hydraulic 
pump 125 for powering the hydraulic systems of the planer 1. 
The right angle drive transmission 124 is mounted adjacent to its 
transverse drive shafts (not shown) on the side tubes 73, 74 by 
transmission support assemblies 126 projecting upwardly from respective 
side tubes 73, 74. The transmission support assemblies 126 are each 
located partly laterally adjacent to and partly behind the rear balast 
compartment 92. 
A pair of actuated jack assemblies 131, which are available under the trade 
name "Jactuator", are mounted on respective jack mounts 132 extending 
rearwardly from the back crosstube 76. A pair of jack motors 133 are 
provided for driving the actuated jack assemblies 131 and are mounted on 
the inner depth control carrier plates 85. The actuated jack assemblies 
131 are connected to the back ends of a pair of depth control wheel 
carriages 136, each of which is pivotally mounted on respective depth 
control carrier plates 80, 85. Each carriage 136 includes a pair of pivot 
beams 137 with a pair of depth control wheels 138 mounted therebetween in 
tandem relationship. A pair of cam plates 141 are mounted on the back ends 
of respective jack mounts 132 and each receives a pair of cam rollers 142 
along its outer edge for engaging a respective side member vertical leg 
19. 
II. VIBRATION DAMPER DESCRIPTION 
A vibration damper 151 comprises an integral part of the sub-frame 3 and 
includes lead shot 153 and a lead ingot 155 located in spatial voids 
formed by the structural members of the sub-frame 3. The engine section 
side tubes 56, 57 include spatial voids or bores 152 adapted to receive 
the lead shot 153. The tool section front crosstube 75 encloses a front 
crosstube bore 154 adapted to receive the lead shot 153. The front ballast 
compartment 91 receives a lead ingot 155. The lead ingot 155 is 
dimensionally slightly smaller than the front ballast compartment 91 
whereby a space 156 is formed therebetween and filled with lead shot 153. 
The rear ballast compartment 92 is filled with lead shot 153, as are tool 
section side tube bores 157 and a back crosstube bore 158. The tube bores 
152, 154, 157, 158 are accessed through fill holes 159 in the respective 
members which are welded shut after filling. If necessary, the members may 
be vibrated during filling to settle the lead shot 153 and to provide 
sufficient room for the amount specified for the road planer 1. The front 
and rear ballast compartments 91, 92 are accessible prior to placement of 
the front and rear upper panels 95, 96 respectively. 
The lead shot 153 is preferably random-sized and capable of passing through 
a No. 17/18 mesh. For example, "Illinois Heavy Pack Lead Shot", available 
from the Division Lead Company, Summit, Ill., has been tested and found to 
be suitable for the proposed usage thereof. The Illinois Cold Pack Shot 
comprises both elliptical and spherical particles. Furthermore, the sizes 
of the individual particles vary somewhat. The random-sized Illinois Cold 
Pack Shot not only has superior performance characteristics as will be 
discussed more fully hereinafter, but also is less expensive than, for 
example, spherical shot. The mean diameter size of the shot 153 is in the 
range of approximately 0.030 to 0.040 inches. 
III. PLANER OPERATION 
The planer 1 disclosed herein is intended primarily for removing high spots 
from new concrete-paved surfaces to conform them to specifications and 
also to restore existing concrete-paved surfaces by removing predetermined 
amounts of damaged or deteriorated concrete. Additional applications of 
the planer 1 include longitudinal cutting of anti-hydroplane grooves and 
conditioning of runways, parking lots and various other concrete-paved 
surfaces. 
The cutter head 117 rotates in a counterclockwise direction when viewed 
from the right side of the grader 1 whereby it resists forward motion of 
the grader 1. The cutter head 117 is preferably subjected to substantial 
downward forces to maximize its performance. The downward loading of the 
cutter head 117 is accomplished by extending the hydraulic cylinders 107 
until the hydraulic pressure in the hydraulic system is approximately 600 
pounds per square inch. If the hydraulic pressure exceeds this amount and 
reaches, for example, 800 pounds per square inch, a safety valve is opened 
to prevent damage to the machine and injury to the operator. The weight of 
the lead shot 153, approximately 800 pounds in the disclosed planer 1, 
also facilitates holding the cutter head 117 in contact with the pavement 
surface. Also, the lead shot 153 cooperates with the members of the 
sub-frame 3, the engine 103 and the ingot 155 to damp vibration and also 
to provide ballast. 
Extending the hydraulic cylinders 107 pivots the sub-frame 3 with respect 
to the main frame 1 about the pivot pin 68 and transfers a portion of the 
weight of the main frame 2 and the equipment associated therewith to the 
sub-frame 3. The depth control wheels 138 are located at a desired 
vertical position with respect to the sub-frame 3 by the actuated jack 
assemblies 131. The actuated jack assemblies 131 are preferably used to 
lower the depth control wheel carriages 136 to a level of a predesired 
planing depth. The actuated jack assemblies 131, since they employ 
screw-thread rods, will support the entire weight of the road planer 1 
with the rear wheels 30 lifted off the surface. However, the actuated jack 
assemblies 131 are preferably adjusted by the operator so that the 
downward pressure on the cutter head 117 is slightly less than that 
required to lift the rear wheels 30. 
The hydraulic cylinders 107, on the other hand, are somewhat compressible. 
Furthermore, the entire main frame 2 is designed to flex a limited amount. 
Thus, upon encountering an uneven pavement surface condition, the main 
frame 2 deflects a limited amount which, together with the slight 
compression of the hydraulic cylinders 107, functions to maintain the 
cutter head 117 in substantially consistent contact with the pavement 
surface. Furthermore, the hydraulic cylinders 107 and the actuated jack 
assemblies 131 permit retraction of the cutter head 117 for transporting 
to and from job sites and the like. 
In operation, it is desirable to cool the cutter head 117 to prolong the 
useful lives of the blades 119. Also, it is usually necessary to contain 
at least a portion of the slurry comprising cooling water mixed with 
grindings and tailings. A shroud 161 is provided over the cutter head 117 
and includes a spray bar with water nozzles and intake ducts for removing 
the slurry. The shroud 161 is connected to the cyclo-seperator 43 and 
comprises a part of the cooling and slurry disposal system 41. 
As the sub-frame 3 is raised and lowered by the hydraulic cylinders 107, 
the sub-frame 3 is maintained in a substantially level position with 
respect to the main frame 2 by the cam rollers 142 engaging the side 
member vertical legs 19 to avoid racking or twisting of the sub-frame 3 
relative to the main frame 2. 
IV. VIBRATION DAMPER OPERATION 
In use, the cutter head 117 is a vibration source and vibrates with respect 
to all three spatial axes relative thereto. For purposes of describing the 
present invention, these axes will be referred to as: (1) vertical; (2) 
horizontal (in the direction of planer travel); and (3) axial (along the 
rotational axis of the cutter head 117 extending transverse to the 
direction of travel). Of the three axial components of cutter head 117 
vibration, the vertical is believed to be the most significant with 
respect to potential damage to the blades 119 and performance of the 
planer 1. Even though the blades 119 have diamond cutting edges, continual 
pounding, particularly from vertical vibration, causes damage and a loss 
of cutting ability. Cutter head vibration diverts energy from the cutting 
and planing function of the blades 119 so that the operator must reduce 
the forward speed of the planer 1 in order to maintain cut depth 
uniformity. The engine 103, which is mounted on the sub-frame 3, is also a 
vibration source and contributes to the vibration of the cutter head 117, 
particularly in a vertical mode because of the vertical reciprocation of 
the pistons of the engine 103. 
By absorbing the vibrational energy of the cutter head 117, the vibrational 
movements in all three spatial axes can be reduced for longer blade life 
and a higher forward speed. A particularly effective way to absorb 
vibrational energy is to couple the cutter head 117 to an unconstrained or 
slightly constrained mass. The damper assembly 151 is designed to operate 
as such a slightly constrained mass. Stated generally, the cutter head 
vibrations are transmitted to and absorbed by the lead shot 153 which is 
sized and configured for maximum freedom of movement and vibration within 
the sub-frame 3. The individual particles of the lead shot 153 vibrate 
with respect to each other and also with respect to the members of the 
sub-frame 3. Thus, vibrational energy from both the cutter head 117 and 
the engine 103 is converted to thermal energy which is transferred to and 
dissipated by the sub-frame 3. 
In sizing and configuring the lead shot 153, it is desirable to maximize 
both the potential and kinetic energies of the damper system 151. The 
potential energy U, may be expressed by the following equation wherein "K" 
represents the elastic coordinates of a particular shot particle and "q" 
represents the mass coordinates thereof. Thus, 
##EQU1## 
The kinetic energy "T" is represented by the following forumula wherein "m" 
represents the mass inertial elements of an individual shot particle. 
Thus, 
##EQU2## 
In both of the above equations, the potential and kinetic energies of the 
particle are expressed as sums of particle movement in all three spatial 
axes. Also, it can be concluded from the above formulas that the potential 
and kinetic energies are directly related to the mass, i.e. the density, 
of the lead shot. The density of the lead shot 153 is directly related to 
the size thereof because the smaller shot sizes tend to have smaller 
percentages of void area. With spherical particles, maximum packing 
density is obtained if the individual spheroids are packed in a hexagonal 
close packed configuration, or HCP, which configurization results in a 
minimum amount of void space for a given mass. The elliptical, 
random-sized lead shot 153 utilized by applicant is believed to at least 
partly assume an HCP configuration, although because of the random sizing 
and the elliptical configurations of some of the shot, voids between the 
larger particles are often filled by the smaller particles, whereby 
relatively high density is achieved. 
The above formulas for potential and kinetic energy would tend to indicate 
that the maximum vibration damping capability might be achieved with a 
finely ground powder; however, as the particles become smaller, 
intermolecular attraction forces therebetween increase according to Van 
Der Waals' Equation of State whereby the particles begin to act as a 
single mass. In particular, clumping and bridging of groups of small 
particles occur whereby the groups tend to vibrate relative to each other 
but not amongst their particle components. The resulting restriction of 
movement in the three spatial axes decreases potential and kinetic energy 
according to the above formulas. 
It has been empirically determined that the lead shot 153 sized and 
configured as discussed above maximizes vibration damping capacity at the 
lowest possible cost. The results of field tests conducted by applicant on 
actual road planing equipment and operation with several damping materials 
are shown in FIGS. 5 through 7. FIG. 5 shows the results of vibration 
tests conducted wherein solid lead ingots were used for ballast and for 
vibration damping. It is noted that primary vibrational peaks in all three 
spatial axes occur at approximately 1,000 Hz. or cycles per second. 
The vibration is particularly severe in the vertical mode with secondary 
peaks occurring in the 6 Hz. to 15 Hz. range. Although the solid lead 
ingots have the highest possible density of approximately 0.411 pounds per 
cubic inch and hence provide adequate ballast for the sub-frame 3, because 
they are solid they are relatively poor dampers of vibration. 
Additional tests were conducted with spherical shot, the results of which 
are shown in FIG. 6. As compared to the test results using ingots as shown 
in FIG. 5, the spherical shot greatly reduced vibration in all three 
spatial axes. 
Finally, FIG. 7 shows the results of tests conducted using random-sized 
lead shot 153. The random-sized shot is particularly effective for 
reducing vibration in the vertical axis. In fact, in the vertical axis the 
random-sized shot 153 was approximately as effective as the spherical shot 
in absorbing vibration. Since vibration in the vertical axis is most 
detrimental to performance and blade life, the overall performance of the 
random-sized shot is considered to be nearly the equivalent of the 
spherical shot and hence, because the former is considerably less 
expensive, it is preferred for the vibration damper 151 of the present 
invention. 
The ellipsoidal and spheroidal shot particles are particularly well adapted 
for vibrating with respect to each other because their rounded surfaces 
tend to allow a certain amount of movement and preclude clumping and 
bridging. In operation, the sub-frame 3 filled with the lead shot 153 
becomes significantly warmer than a comparable sub-frame 3 provided with 
lead ingots, which indicates that the lead shot 153 functions as an 
effective transducer for converting vibrational energy from the engine 103 
and the cutter head 117. Furthermore, the configuration of the sub-frame 3 
is particularly designed for effective vibration transfer from the engine 
103 and the cutter head 117 to the slightly constrained mass comprising 
the lead shot 153. Specifically, the engine mounts 61, 102 are placed on 
the engine section side tubes 66, 67 and the tool section front crosstube 
75 respectively, all of which are filled with the lead shot 153. Vibration 
from the right angle drive transmission 124 is transmitted through the 
transmission support assembly 126 directly to the tool section side tubes 
73, 74. Vibration from the cutter head 117 is transmitted through the 
cutter head mounting brackets 111 directly to the tool section side tubes 
73, 74. Finally, the ballast compartments 91, 92 are located whereby much 
of the vibrational energy from both the engine 103 and the cutter head 117 
will be transferred thereto. 
As compared to the same planer 1 without damping, it has been determined 
that operating speeds of approximately 20% faster may be achieved by 
employing the lead shot 153 for vibration damping and balast than with 
solid lead ingots used for balast alone. 
The random-sized shot 153 has a density of approximately 0.371 pounds per 
cubic inch, or approximately 90% of the density of solid lead whereby the 
void volume in the shot 153 equals approximately 10% of its total volume. 
The road planer 1 weighs approximately 38,000 to 40,000 pounds and a total 
weight of lead shot 153 of approximately 800 to 1,000 pounds is employed. 
It is to be understood that while certain forms of the present invention 
have been illustrated and described herein, it is not to be limited to the 
specific forms or arrangement of parts described and shown.