Log splitter

There is claimed a log splitter comprising means for penetrating a log, a handle pivotally mounted for manual operation, a cam shaped sheave which is rotated by rotation of the handle, a ratchet and pawl assembly which transmits force from the handle to the sheave, a drive cable attached so that it is wound onto said sheave, and as said drive cable is wound onto the sheave it causes a sharpened edge to penetrate the log, splitting the log, and the cam shape of the sheave produces large mechanical advantage as the log is initially penetrated, and lesser mechanical advantage but greater travel distance as the penetration continues.

BACKGROUND OF THE INVENTION 
This invention relates generally to manually operated devices for splitting 
logs. This invention is particularly adaptable to the manual splitting of 
logs for use in a fireplace, a wood burning stove, or the like. 
A particularly novel and useful feature of the device is a cam shaped 
sheave that winds up a drive cable and thereby draws a log penetrating 
wedge into the log. The cam shape allows a high mechanical advantage as 
the log is first penetrated, and a progressively lower mechanical 
advantage but greater travel distance of the wedge as the log is further 
split. 
A further novel feature of the present invention is a manually operated 
handle which operates a ratchet and pawl assembly. The ratchet rotates the 
sheave and draws the wedge into the log. 
Manually operated log splitters of the prior art have employed direct 
gearing to transmit rotation of a handle into penetration of the log. A 
major disadvantage of the prior art is that downward force on the handle 
causes upward rotation of the frame of the log splitter. A further 
disadvantage of the prior art is that the force on the log is not greatest 
just as penetration of the log begins. In contrast, motion is reversed by 
the drive cable of the present invention, and downward force on the handle 
causes the log splitter to remain stationary. 
Other prior art manual log splitters employ a complex arrangement of 
pulleys and levers, and attempt to split the log along its long dimension. 
In contrast, the present invention is a compact device which is easy to 
use. Fireplace logs can be easily split by a small person of weight 110 
pounds or less by his/her simply operating the handle. The large 
mechanical advantage produced by the cam shaped sheave makes splitting of 
logs very easy with the present invention.

SUMMARY OF THE INVENTION 
There is claimed a log splitter comprising: 
means for penetrating a log; 
means for holding said log against the force exerted upon said log by said 
means for penetrating said log; 
a handle pivotally mounted at a first end and manually moved in an arcuate 
path at a second end; 
a drive cable attached at a first end so as to provide said force between 
said means for penetrating said log and said means for holding said log; 
a sheave rotatably mounted for the purpose of having said drive cable wound 
about its exterior surface; 
means for winding a second end of said drive cable onto said exterior 
surface of said sheave by said arcuate motion of said handle; 
a frame which supports the parts of said log splitter; 
whereby arcuate motion of said handle rotates said sheave causing said 
drive cable to wind about the exterior surface of said sheave and said 
winding causes the distance between said means for penetrating said log 
and said means for holding said log to decrease, thereby exerting 
compressive force upon said log and causing said means for penetrating 
said log to penetrate said log and split said log. 
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
An embodiment of the invention which has been found to perform well is 
herein described. Referring to FIG. 1, a side view of the log splitter is 
shown. A frame 20 is welded from angle iron and steel plate. Two long 
members 22 and 24 are formed from angle iron of approximate dimension 21/2 
inches.times.21/2 inches.times.1/2 inch and are approximately 48 inches 
long. Referring to FIG. 7 and FIG. 8, members 22 and 24 each have two 
sides of material joined at essentially right angles. A first side 26 of 
the first member 22 is spaced apart from and essentially parallel to a 
first side 30 of the second member 24. Side 26 of the first member 22 is 
spaced approximately 1-1/16 inch from side 20 of the second member 24. A 
rectangularly shaped space 25 is formed between sides 26 and 30. 
Both member 22 and member 24 are joined, as by welding, to a front frame 
plate 32. Front frame plate 32 may be made of 1/4 inch steel plate. Also 
both member 22 and member 24 are joined, as by welding, to a rear frame 
plate 34. Rear frame plate 34 may be made of angle iron of dimension 
21/2.times.21/2.times.1/2 inches. Secure joinder, as by welding, of 
members 22 and 24 to front frame plate 32 and to rear frame plate 34 
maintain the spacing of sides 26 and 30 so that they maintain their 
essentially parallel orientation. A bumper plate 36 made of approximately 
1/4 inch steel plate, is attached, as by welding, between sides 26 and 30. 
A resilient material 38 such as rubber is attached to bumper plate 36. 
Wheels 42 are rotatably attached to an axel 44, and axel 44 is attached to 
rear frame plate 34. A bent projection 46 of front frame plate 32 serves 
as a front support for the frame 20. 
A backstop 50 holds a log 52 against force exerted upon the log 52 by the 
wedge 54. Backstop 50 is formed out of approximately 1/2 inch steel plate. 
Backstop 50 has two surfaces, a bottom 56 and a back 58, and also a brace 
60. Two claws 62 and 64 extend below bottom 56 of backstop 50 and lock 
into holes 66. Holes 66 are cut in horizontal side 70 of first frame 
member 22 and horizontal side 72 of second frame member 24. Holes 66 are 
essentially rectangular in shape. Holes 66 are cut with essentially 
parallel sides. The front side 74 of hole 66 and the back side 76 of hole 
66 are at an angle of approximately 5 degrees to the vertical. Making 
holes 66 approximately 5 degrees off vertical improves the stability of 
backstop 50 when force is brought against back 58 by log 52. 
Holes 66 are located in pairs so that backstop 50 can be located to 
accommodate logs 52 of different lengths. The plane of back 58 of backstop 
50 is essentially perpendicular to the long dimension of frame members 22 
and 24. The force exerted against back 58 by log 52 will be approximately 
equally distributed between the two claws 62 and 64 of backstop 50. 
The wedge carriage 86 is made of essentially 1/2 inch steel plate. 
Referring to FIGS. 5, 7, 10 and 11, there are two axles 90 and 92 fixedly 
mounted to wedge carriage 86. Axle 90 is mounted above the horizontal 
sides 70 and 72 of frame members 22 and 24. Wheels 94 are rotatably 
mounted on axle 90. Wheels 94 roll along upper surfaces 96 and 98 of sides 
70 and 72. Wheels 94 are made in the form of two cylinders. The outer 
cylinder 102 is of smaller diameter than the inner larger cylinder 104. 
Referring to FIG. 10, the larger diameter cylinder 104 serves as a spacer 
between the first side 26 of frame 22 and the adjacent side 106 of wedge 
carriage 86. Likewise the larger diameter cylinder 108 serves as a spacer 
between surface 30 of frame member 24 and the corresponding surface 110 of 
the wedge carriage 86. The smaller diameter cylinder 102 and 112 serve as 
wheel surfaces by rolling along the horizontal surfaces 70 and 72 of frame 
members 22 and 24. 
Wheels 113 are likewise made of two cylinders, with an inner large diameter 
cylinder 114 and smaller outer diameter cylinder 115. The large diameter 
cylinders maintain spacing of the wedge carriage 86 within space 25, and 
the small diameter cylinders serve as wheels and roll along the bottom 
surfaces 116 and 117 of members 22 and 24. The wedge carriage 86 is 
maintained essentially centered in the space 25. 
The wedge blade 119 may be made out of 1/2 inch thick high carbon steel, 
with a sharpened, hardened edge 120. A triangular shroud 122 is attached, 
as by welding, with its apex affixed to the wedge blade 119 slightly to 
the rear of the hardened edge 120. The hardened edge 120 penetrates the 
log 52 which is to be split, and upon entering into the wood, the 
triangular shroud 122 facilitates further splitting of the wood. 
A handle 130 is used to rotate a sheave 132. As sheave 132 rotates, it 
winds up a cable 134, one end of which is fixedly attached to the sheave 
132. The other end of the cable 134 is fixedly attached to the wedge 
carriage 86. As the cable 134 winds up on sheave 132, the hardened edge 
120 of the wedge blade 119 is drawn by cable 134 against log 52 with 
sufficient force to penetrate and split log 52. Either a 3/8 inch diameter 
steel stranded cable or a leaf chain of the type sold by Morse Chain Div. 
of Borg Warner Corporation of average ultimate strength of 18,000 pounds 
or more has proven satisfactory as cable 134. Cable 134 is wound onto 
sheave 132 by rotation of handle 130. The handle 130 is rotatably mounted 
on drive shaft 140. Referring to FIGS. 1, 2 and 3, drive shaft 140 is 
rotatably mounted in the first bearing support plate 142 and the second 
bearing support plate 144. The first bearing support plate 142 is fixedly 
attached, as by welding, to first frame member 22. The second bearing 
support plate 144 is fixedly attached, as by welding, to second frame 
member 24. The two bearing support plates 142 and 144 are mounted 
essentially parallel. The two bearing support plates 142 and 144 may be 
fixedly attached, as by welding, to an end plate (not shown). The bearing 
support plates 142 and 144 may be made of approximately 1/2 inch thick 
steel plate. The drive shaft 140 is rotatably mounted between the two 
bearing support plates 142,144. The axis of drive shaft 140 is essentially 
perpendicular to the long dimension of the frame 20. Drive shaft 140 has 
been found to be satisfactory when made of approximately 11/4 inch 
diameter steel shaft. Drive shaft 140 is mounted in bearings 143. Bearings 
143 are mounted in bearing support plates 142 and 144. 
A ratchet wheel 150 is fixedly mounted on drive shaft 140, as by use of a 
key and channel mounting. Referring to FIG. 2, Channel 152 is cut in 
ratchet wheel 150, and Channel 154 is cut in drive shaft 140, and a Key 
156 lockingly holds ratchet wheel 150 onto drive shaft 140. Alternatively 
it has been found satisfactory to weld ratchet wheel 150 to drive shaft 
140. Inertial welding wherein heat generated by friction from spinning 
shaft 140 within ratchet wheel 150 may be used to accomplish this weld. 
The sheave 132 is fixedly mounted on drive shaft 140, as by use of key and 
channel mounting (not shown). The sheave 132 is mounted between the two 
bearing support plates 142 and 144, and additionally the sheave is 
essentially centered above the space 25. An idler pulley 157 is rotatably 
mounted between bearing support plates 142 and 144, and essentially 
centered over space 25. Idler pulley 157 guides cable 134 between sheave 
132 and wedge carriage 86. 
Rotation of handle 130 is transmitted to the drive shaft 140 by means of 
drive pawl 160. Drive pawl 160 is rotatably mounted on axle 161. Axle 161 
is fixedly mounted to handle 130. Drive pawl 160 bears against the teeth 
162 of ratchet wheel 150 as handle 130 is moved in a downward direction. 
Drive pawl 160 causes ratchet wheel 150 to rotate, the rotation of ratchet 
wheel 150 is transmitted to drive shaft 140, and the rotation of drive 
shaft 140 in turn causes sheave 132 to rotate. Upward motion of handle 130 
causes drive pawl 160 to slidably move around ratchet wheel 150. Spring 
164 keeps drive pawl 160 in contact with ratchet wheel 150. 
Holding pawl 170 is rotatably mounted on axle 172. Axle 172 is fixedly 
attached to bearing support plate 142. A spring 320 may be used to hold 
holding pawl 170 in contact with the teeth 162 of ratchet wheel 150 as 
shown in FIG. 15. An alternative means of maintaining contact between 
holding pawl 170 and ratchet wheel 150 is to make the far end 174 of 
holding pawl 170 heavier than the near end 176 so that the force of 
gravity causes the near end 176 to rotate upwardly and to engage the teeth 
162 of ratchet wheel 160. Holding pawl 170 prevents the ratchet wheel 150 
from rotating backwards and allowing the cable 134 to unwind from sheave 
132. Holding pawl 170 may be provided with a foot pedal (not shown) to 
provide a convenient means for the operator to release holding pawl 170 
from ratchet wheel 150, thereby allowing sheave 132 to rotate backwards 
and the cable 134 to unwind from sheave 132. Alternatively a trip chain 
180 may be used to release holding pawl 170. Holding chain 180 is fixedly 
attached to trip lever 182. Trip lever 182 is rotatably mounted on axle 
184. Axle 184 is fixedly attached to handle 130. Trip chain 180 is 
attached at one end to trip lever 182 and at the other end to holding pawl 
170. When handle 130 is rotated into an extreme upward position, trip 
chain 180 causes rotation of both holding pawl 170 and trip lever 182. The 
rotation of holding pawl 170 releases holding pawl 170 from the ratchet 
wheel 150. The rotation of trip lever 182 causes its surface 186 to 
contact surface 190 of drive pawl 160, thereby causing rotation of drive 
pawl 160 and consequently releasing ratchet wheel 150, so that ratchet 
wheel 150 is free to turn backwards and the cable 134 may then unwind from 
sheave 132. Other methods of conveniently releasing drive pawl 160 and 
holding pawl 170 so that the sheave 132 may turn backwards and cable 134 
may then unwind from sheave 132 will be obvious to a person skilled in the 
art. The angle to which the handle 130 must be raised in order to release 
ratchet wheel 150 may be adjusted by adjusting the link of trip chain 180 
which is held in fingers 192 of holding pawl 170. 
Cable 134 is wound upon sheave 132 by downward motion of handle 130, and 
the force causing rotation of sheave 132 is transmitted by drive pawl 160 
from handle 130 to ratchet wheel 150. The rotation of ratchet wheel 150 is 
transmitted to sheave 132 by rotation of drive shaft 140. Cable 134 draws 
the wedge carriage 86 toward log 52 as cable 134 is wound onto sheave 132. 
Cable 134 is guided by idler pulley 157. As wedge carriage 86 begins its 
motion, the edge 120 of the wedge 119 is drawn into contact with log 52, 
and begins penetration of log 52. At the beginning of penetration of log 
52, the wedge carriage is ideally positioned against bumper 36, and the 
cable 134 is fully unwound from sheave 132. 
Referring to FIG. 1, the cable 134 is shown in the fully unwound 
configuration. Log 52 is placed in position for splitting, and backstop 50 
is positioned to hold log 52 against the force of edge 120. In the 
position shown in FIG. 1, the handle provides a long lever arm for 
application of force by the operator, and the distance from the center of 
drive shaft 140 to the cable at location 200 provides the lever arm for 
application of force to the edge 120 against log 52. As rotation of sheave 
132 initially begins, the distance from the center of drive shaft 140 to 
location 200 is approximately one inch. The end of handle 130 is 
approximately 5 feet 6 inches from the center of drive shaft 140, or a 
distance of approximately 66 inches. The theoretical mechanical advantage 
is therefore approximately 66 to 1. If approximately 100 pounds of force 
are applied to the end of handle 130, then approximately 6,600 pounds, or 
3.3 tons of force will be applied to log 52 along edge 120, with some 
subtractions to account for friction within the device. As the cable winds 
upon sheave 132, the distance between the center of drive shaft 140 and 
location 200 increases because of the cam shape of sheave 132, and the 
mechanical advantage therefore decreases. It is convenient to have the 
mechanical advantage decrease as the log 52 is further penetrated because 
the force required to continue splitting a log is much less than the force 
required to initially split the log. And as the mechanical advantage 
decreases, the distance of travel of wedge carriage 86 increases, for a 
given angular rotation of handle 130. It is convenient to decrease the 
mechanical advantage as the log is split in order to reduce the amount of 
motion of the handle which is needed to complete motion of edge 120 into 
the log for completion of splitting of the log. Cable 134 is fixedly 
attached to sheave 132 at location 201. 
A return spring 210 and a return cable 212 apply force to the wedge 
carriage 86 to return it against backstop 36. When the drive pawl 160 and 
the holding pawl 182 are released to permit backward rotation of ratchet 
wheel 150, then return spring 210 through return cable 212 pulls the wedge 
carriage 86 into position against backstop 36, and unwinds the cable 134 
from sheave 132. Alternatively a compression spring 300 may be used to 
return wedge carriage 86 to position against backstop 36, as shown in FIG. 
14. Referring to FIG. 8, a fixed stop 230 and a sheave mounted stop 240 
serve to limit the rotational motion of sheave 132. 
Alternatively the wedge which penetrates the log may be fixedly mounted 
upon the frame, and the movable carriage then bears against the log by 
means of a flat plate and drives the log onto the wedge, as shown in FIG. 
14. Alternatively the wedge may be replaced by a cone-shaped penetrating 
element 310 with a sharpened hardened point which penetrates the log, as 
shown in FIG. 16B. Other shaped penetrating elements may be substituted 
for the wedge. 
The foregoing description of the invention has been directed to a preferred 
embodiment in accordance with the requirements of the Patent Act, for the 
purpose of explaining the invention and not for the purpose of limiting 
the scope and spirit of what has been disclosed herein. It will be 
apparent to persons skilled in the art that modifications may be made in 
the device disclosed herein to suit the device to different materials. The 
claims appended hereto are intended to set forth the true scope and spirit 
of the invention, including but not being limited to the particular 
embodiments disclosed hereinabove.