METHOD AND APPARATUS FOR DRIVING A CUTTING BLADE IN A SELF-PROPELLED SAW

METHODE ET DISPOSITIF POUR ENTRAINER LA LAME DE COUPE DANS UNE SCIE AUTOMOTRICE

English Abstract

Conventional self propelled saw cutting machines utilize air cooled transversely mounted, internal combustion engines. The engine drives a rotatable circular saw blade through a series of pulleys or chain drives. Since the saw is driven at substantially ninety degrees to the engine output shaft this places a considerable side loading on the crankshaft and bearings. In addition the air intake of the engine is in line with and rearward of the saw blade and thus contaminants from the saw cut are drawn into the engine. The method and apparatus of the present inven- tion eliminates both problems by mounting the engine "in-line" with the vehicle frame rather than transversely. This significantly reduces the likelihood of saw cut contaminants entering the engine air intake. A differential assembly is coupled to the output shaft of the engine and, through a pulley system, drives a rotatable axle shaft to which is coupled the saw blade. Mounting the engine "in-line" with the frame opens the possibility of using diesel engines to power the vehicle without increasing the vehicle width and with no loss in maneuverability.

French Abstract

Les machines de sciage automotrices conventionnelles emploient des moteurs à combustion interne montés transversalement et refroidis par air. Le moteur entraîne une lame de scie circulaire rotative grâce à une série de poulies ou de transmissions par chaîne. Étant donné que la scie est entraînée à quatre-vingt-dix degrés, sensiblement, par rapport à l'arbre de sortie du moteur, le vilebrequin et les paliers sont soumis à une charge latérale considérable. De plus, l'admission d'air du moteur est dans l'alignement et à l'arrière de la lame de scie et, de ce fait, les contaminants issus du sciage sont aspirés dans le moteur. Le procédé et le dispositif de la présente invention éliminent ces deux problèmes du fait du montage du moteur « en ligne » avec le châssis de véhicule plutôt que transversalement. Cela réduit significativement la probabilité de voir les contaminants du sciage pénétrer dans l'admission d'air du moteur. Un ensemble différentiel est couplé à l'arbre de sortie du moteur et, par un système à poulie, entraîne un arbre de roue auquel est couplée la lame de scie. Le montage du moteur « en ligne » avec le châssis offre la possibilité d'utiliser des moteurs diesel pour mouvoir le véhicule sans accroître la largeur du véhicule et sans dégradation des facilités de manuvre.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A self propelled sawing machine having a frame, a pair of wheel assemblies
to
support said frame and located at spaced locations along the longitudinal axis
of said
frame, an internal combustion engine supported by said frame and having an
output shaft
disposed for rotation about an axis generally parallel to said longitudinal
axis, a first
transmission to transfer power from said engine to one of said wheel
assemblies to propel
said machine, and a second transmission to transfer power from said output
shaft to a saw
blade mounted for rotation about an axis transverse to said longitudinal axis.
2. A self propelled sawing machine according to claim 1 wherein said saw blade
is
mounted on a driven shaft rotatably supported on said frame and said second
transmission drives said driven shaft at spaced locations along said driven
shaft.
3. A self propelled sawing machine according to claim 2 wherein said second
transmission includes an angle drive to drivingly connect said output shaft to
a drive shaft
disposed transverse to said longitudinal axis.
4. A self propelled sawing machine according to claim 3 wherein said drive
shaft
extends laterally to opposite sides of said output shaft and is connected to
said driven
shaft at said spaced locations on opposite sides of said drive shaft.
5. A self propelled sawing machine according to claim 4 wherein said drive
shaft is
connected to said driven shaft by a pair of belt drives.
6. A self propelled sawing machine according to claim 3, 4 or 5 wherein said
angle
drive includes a differential gear assembly.
7. A self propelled sawing machine according to claim 6 wherein said output
shaft is
connected to a pinion gear of said differential gear assembly.

2
8. A self propelled sawing machine according to any preceding claim where each
of
said wheel assemblies are located to one side of said driven shaft whereby
said saw blade
is disposed adjacent one end of said machine.
9. A self propelled sawing machine according to any preceding claim wherein
said
internal combustion engine is a diesel engine.
10. A self propelled sawing machine according to any preceding claim wherein
said
driven shaft has a mounting plate to receive said saw blade at one end
thereof.
11. In a self propelled sawing machine of the type having a frame with front
and rear
ground engaging wheel assemblies, an engine driven hydrostatic transmission
mounted to
the frame and drivingly engaging one of said wheel assemblies, a circular saw
blade
rotatably mounted on the frame and drivingly connected to the engine for
making cuts in
concrete and the like, a method for the elimination of engine crankshaft side
loading
comprising the steps of:
mounting an internal combustion engine, upon the frame with the axis of
rotation
of the output shaft aligned with the longitudinal axis of said frame;
connecting a differential assembly to said output shaft of the engine so that
the
output shaft of the engine drives the pinion gear of the differential
assembly, and said
differential assembly provides a drive shaft disposed transverse to said
longitudinal axis;
mounting a circular saw blade to a pulley driven axle shaft disposed
transverse to
said longitudinal axis; and
connecting the axle shaft pulley to the output of the differential assembly
with at
least one drive belt.

Description

213~572
PATENTAPPLICATION OF
Rick Trottier for a
METHODANDAPPARATUS FOR DRIVINGA CU7'rING BL ADE IN
A SELFPROPELLED SAW
Field of the Invention.
This invention relates to concrete cutting saw blades as used with internal combustion
engine powered, self propelled saws; more specifically to a method and apparatus of driving
the saw blade such that engine crankshaft deflection caused by side loading is substantially
eliminated.
Background - Known Art.
Gasoline engine powered cutting machines using circular saw blades find many applica-
tions within the construction industry, such as paving and masonry cutting.
In essence, such machines are com~)l;sed of a wheeled frame with a transversely mounted,
air cooled, gasoline engine. The engine drives the rear wheels via a hydrostatic or manua]

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transmission and at the same time powers a circular saw blade through a belt or chain driven
pulley system.
Not ~ul~lisingly, much inventive ingenuity has been applied to the design of such ma-
chines over the years and currently available machines are much more efficient and easier to
control their older counterparts.
While undoubtedly considerably improved over older devices, current sawing machines
nevertheless suffer from several shortcomings in that, with a transverse mounted engine the
saw blade must be driven at a right angle to the engine output shaft. Such an angular drive
arrangement subjects the engine crankshaft to considerable side loading - loading the crank-
shaft and bearings were never designed to absorb - and necessitates the use of complex bear-
ing block mechanisms to alleviate this problem.
In addition the design of current machines places the engine air intake in line with, and
rearward of the saw blade, thus exposing the engine cooling air intake to dust and debris
produced by the blade cuttings and decreasing engine life considerably.
Using saw blades of differing diameters requires a change in pulley diameter in order to
obtain ap~lo~liate blade rotational speeds and, since the design of current machines places
the relevant pulleys and sheaves in a generally in~ccessible position, pulley and sheave changes
usually result in a relatively complex procedure thereby contributing to long machine down
time.
It is desirable, then, to devise a self propelled concrete saw wherein engine crankshaft
deflection is eliminated and the engine air intake is not directly exposed to the debris from the
saw blade cuttings. It is also desirable to utilize the inherent advantages offered by a diesel
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~engine over those of conventional gasoline powered engines, e.g., higher fuel efficiency, better
power curve, more constant torque, and smoother governor operation, all of which serve to
produce a relatively more stable saw blade r.p.m.
Objects and Advantages
Several objects and advantages of the present invention are:
a) to provide a self propelled concrete saw wherein the form of motive power is a diesel en-
glne;
b) to provide a self propelled concrete sawwherein the engine is mounted "in-line" rather than
transversely; and
c) to provide a self propelled concrete saw wherein the accommodation of differing blade
diameters entails a minimum of machine down time by eliminating the need for pulley and
sheave changes and replacing this relatively complex procedure with a simple operation of
subsliluling a differential assembly with a gear reduction appropriate to a given saw blade
diameter.
Other objects and advantages of the present invention are to provide a self propelled
concrete saw the overall dimensions of which compare favorably with those of conventional
machines; and to provide a self propelled concrete saw the maneuverability of which is no less
than that of conventional machines.
Other objects and advantages will become apparent from a consideration of the ensuing
description and drawings wherein:
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Figure 1 is a schematic re~resentation of a conventional self propelled concrete saw;
Figure 2 is a schematic representation of the self propelled concrete saw of the present inven-
tion showing the major differences over the conventional device;
Figure 3 is a side view of the blade drive mechanism of the present invention; and
Figure 4 is an end on view of the blade drive mechanism of the present invention.
Description.
An understanding of the significance of the present invention may be achieved by com-
parison of the col,lponent configuration of a conventional machine as shown in figure 1 with
that of a preferred embodiment of the present invention as illustrated in figure 2.
Referring to figure 1 it will be seen that a conventional saw cutting machine, generally
designated 10, is coll,p~ised of a frame 18 having a pair of ground contacting front wheels 24
and a pair of ground contacting rear wheels 20. A transversely mounted engine 16 is mounted
to the frame 18 and drivingly connected by conventional means 36 to a circular saw blade 28
which blade 28 is rotatably mounted to the frame 18.
The engine 16 is also drivingly connected to a conventional hydrostatic transmission 30
which is, in turn drivingly connected by conventional means 34 to the frame 18 rear wheels 20.
A housing incorporating a pushing and steering handle 12 is attached to the frame 18.
A shift lever 14 is connected by conventional means 32 to a control arm of the hydro-
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static transmission 30 to control the rotational direction of the transmission 30 output shaftthus providing for~vard and reverse driving power to the rear wheels 20.
Referring now to figure 2 it may be seen that the embodiment of the present invention
differs significantly from that of the con~elltional machine in that the preferred embodiment is
colllplised of an engine 16, either diesel or gasoline powered, mounted upon frame 18 in an
"in-line" position with the front of the engine 16 toward the rear of the machine 10.
A conventional differential assembly 40is drivingly coupled to the output shaft of the
engine 16 by conventional means 44 so that the output power of the engine 16 is effectively
split and delivered at right angles to a pair of pulleys 52, each pulley 52 rotatably connected to
the differential assembly 40.
Refer to figures 2 and 3.
The engine 16, either diesel or gasoline, is mounted to the frame 18 "in-line" and sub-
stantially centered on the frame 18 and secured to the frame 18 by means of conventional
- engine mounts 48.
A differential assembly 40 of conventional design and having a pair of axially opposed
mu!ti-grooved pulleys 52 is attached to the rear of the engine 16 by conventional coupling
means 44 such that the output shaft of the engine 16 acts as the pinion for drivingly engaging
the crown gear of the differential assembly 40 thus effectively transmitting the output driving
power of the engine 16 at right angles to each of the differential pulleys 52.
A rigid, robust axle shaft 50 incorporates a pair of multi-grooved pulleys 48, each pulley
48 of a diameter proportionate to that of the pulleys 52 of the differential 40 such that the
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combination of pulleys 48 and pulleys 52 results in an appl op, iate drive speed for a given saw
blade 28 diameter. Each pulley 48 is spaced apart on the axle shaft 50 such that when the axle
shaft 50 is af~ed to the underside of the frame 18 by conventional bearing block means 46 the
axle shaft 50 pulleys 48 are aligned with the differential pulleys 52 and the differential pulleys
52 are drivingly connected to the COll esponding axle shaft 50 pulleys 48 by conventional drive
belt means 36 which pass through appropriate apertures in the frame 18.
Conventional saw blade mounting plates 42 are connected by conventional means toeither end of the axle shaft 50 and the saw blade 28 mounted thereon.
From the above it will be understood that, unlike conventional machines, no significant
crankshaft deflection occurs and that the engine air intake, whether diesel or gasoline, is re-
moved from the path of dust and debris created by the saw blade cuttings.
It will also be understood that the rotational speed of the saw blade 28 is determined by
the gear ratio of the differential assembly 40 and the engine 16 RPM. Installing a blade of
greater or smaller diameter entails only that a differential assembly 40 with an appropriate
gear reduction be installed to the rear of the engine 16. Since this area is readily exposed by
removal of any protective cowlings ch~nging the differential assembly 40 is a relative~ minor
job requiring little machine down time.
Summary
The present invention, by employing an "in-line" mounted engine coupled to a conven-
tional differential to provide right angle drive eliminates cr~nk~h~ft deflection while facilitat-
ing blade size changes. In addition, this engine configuration effectively reduces the likelihood
of cont~min~nts entering the engine air intake system, and thus reduces maintenance require-
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2135572
ments. Mounting the engine "in-line" opens the way to effectively employ diesel engines as the
power source in saw cutting machines with all the attendant advantages of such engines over
conventional gasoline engines, and with substantially no increase in vehicle width or loss of
maneuverability.
The above des~ tion should not be construed as limiting the scope of the present in-
vention but rather as simply a description of a presently preferred embodiment. It should be
clear that many variations on the placement of components is possible without departing from
the spirit of the invention. For example the placement and means of connecting driving power
to the hydrostatic transmission is open to great variation while the configuration of the control
console may remain as that used by conventional machines. Likewise, whether drive belts or
chain drives are used to connect the differential pulleys to the axle shaft pulleys is, in and of
itself of little consequence.
Thus the scope of the invention should be determined by the appended claims and their
legal equivalents.

Representative Drawing