Lawn edging machine

A balanced self-propelled and manually guided lawn edger is disclosed in which an edging cutter blade is positioned near the inner side and rearwardly of the larger of two traction wheels of unequal diameters on a common drive axle. The smaller traction wheel can be axially adjusted relative to the larger wheel to regulate the angle of cut adjacent to a side wall or curbing.

BACKGROUND OF THE DISCLOSURE 
The objective of the invention is to provide an improved lawn edger of the 
self-propelled hand-guided type. Commonly such machines have three or four 
wheel carriages wherein the edging and trimming blade is held in a fixed 
location above the ground and cannot be raised and lowered or otherwise 
adjusted by mere manipulation of the machine guidance handles. Other known 
lawn edgers include tiller type rotary edging blades which are power 
driven. In general, such machines are rather complicated and quite costly. 
In light of the deficiencies of the known prior art, the present invention 
seeks to provide a more efficient and less costly lawn edging machines of 
the self-propelled hand-guided type wherein the depth of cut of an angled 
edging blade may be regulated merely by tilting the machine guidance 
handles around the axis of two coaxial traction wheels which form the 
carriage of the machine. 
In accordance with the invention, the two traction wheel are of unequal 
diameters to establish the cutting angle of an edging blade located near 
and inwardly of the larger traction wheel and somewhat behind the drive 
axis of the latter. The cutting angle of the blade can be varied 
conveniently by adjusting the smaller traction wheel axially toward and 
away from the larger wheel. The height of the edging blade can also be 
adjusted on the frame of the machine. 
Other features and advantages of the invention will become apparent during 
the course of the following detailed description.

DETAILED DESCRIPTION 
Referring to the drawings in detail wherein like numerals designate like 
parts, a lawn edging machine in accordance with the invention includes a 
frame 10 having a platform portion 11 for the support of a conventional 
engine 12 having a fuel tank 13 and carburetor 14. Guiding handles 15 rise 
from the frame 10 and extend rearwardly thereof to enable a walking 
attendant to manipulate and guide the edging machine. One handle 15 
includes a conventional speed control 16 while the other handle is 
equipped with a belt transmission engage and disengage lever 17. 
A conventional belt transmission for the machine includes an upright 
housing 18 including an upper input shaft 19 journaled thereon and 
carrying an external input pulley 20, engaged with a transmission belt 21 
connected between the pulley 20 and a drive pulley on the crank shaft of 
engine 12. A belt driven pulley, not shown, within the lower part of 
housing 18 is coupled to the transverse axle shaft 22 of a comparatively 
large traction wheel 23 to power the latter. 
A smaller wheel 24 spaced laterally from the larger wheel 23 is rotatably 
held on a shaft section 25 which engages telescopically through a hub 26 
secured to the lower part of transmission housing 18. The shaft section 25 
has spaced adjusting holes 27 formed therein adapted to register 
selectively with a single aperture 28 of hub 26 whereby a locking pin 29 
can be utilized to releasably lock the shaft section in any of several 
axially adjusted positions within the hub 26, in accordance with an 
important feature of the invention. During adjustment inwardly or 
outwardly relative to the hub 26, the shaft section 25 may also telescope 
with the driven shaft 22 of the larger traction wheel 23. The smaller 
wheel 24 is not a driven wheel and turns freely at any required speed on 
the shaft section 25. 
An edging blade 30 preferably in the form of a disc is fixed by bolt means 
31 to a rigid support arm 32 which depends from the frame 10 of the 
machine. The arm 32 is vertically adjustable through the selective 
cooperation of adjusting notches 33 in one edge thereof with a locking pin 
34 held within an opening of frame 10 and adapted to enter a selected 
notch 33 to lock the arm 32 and blade 30 at the selected elevation 
relative to the frame 10 and ground wheels of the machine. Additional bolt 
openings 35 are provided in the disc blade 30 so that the blade can be 
turned and locked in several new positions on the arm 32 as wear gradually 
occurs in its cutting edge. 
The blade 30 is thus positioned somewhat rearwardly of the axle shaft of 
the machine and near and inwardly of the larger driven wheel 23, at a 
fixed distance from this wheel. The distance of the smaller wheel 24 from 
the blade 30 and from the larger wheel 23 may be adjusted by use of the 
cooperating means 27, 28 and 29 to vary the angle of inclination of the 
blade 30 to the ground as depicted in FIGS. 5 and 6. As shown in FIG. 5, 
when the wheel 24 is extended from the larger wheel 23 and blade 30, the 
angle of the blade to the vertical is less than in FIG. 6 where the 
smaller wheel is adjusted to its closest position to the larger wheel and 
blade. This simple arrangement enables the user of the machine to vary the 
profile of the small trench formed by the blade 30 along one edge of a 
curbing, sidewalk or other pavement. 
The edging machine is characterized by simplicity of construction, ease of 
adjustment, convenience of use, good balance, and it is also rugged and 
durable. It is a comparatively safe machine because rotation is not 
imparted to the blade 30 and the blade does not throw dirt or stones into 
the face of the user or others nearby. 
It is to be understood that the form of the invention herewith shown and 
described is to be taken as a preferred example of the same, and that 
various changes in the shape, size and arrangement of parts may be 
resorted to, without departing from the spirit of the invention or scope 
of the subjoined claims.