Mechanical earthworm harvester

A vibrating, moving, endless screen for separating earthworms from worm castings and bedding. An endless belt fabricated from a screen is placed on an incline and moved upwardly in the direction of the incline. A portion of the moving surface is vibrated and a mixture of worm bedding, castings and earthworms is placed along the upper surface. The worms are conveyed over the upper end of the belt. The worm castings and bedding fines pass through the belt and the larger bedding material passes downwardly over the screen surface and passes over the lower end of the moving endless belt.

BACKGROUND OF THE INVENTION 
The production of earthworms for bait, animal feed and agricultural 
purposes is a growing business. Typically, earthworms are raised in worm 
beds and when the worms are mature they must be separated from the bedding 
material and from the worm castings. The worm castings have been 
recognized as a highly effective organic fertilizer and the re-claiming of 
this resource has become a valuable adjunct to the business of raising 
earthworms. 
The separation of earthworms from other bedding material has classically 
been carried out by placing the mixture on the upper surface of a screen 
which is typically tilted or shaken to permit the castings to pass through 
the screen and to hold the worms on the upper surface of the screen. Such 
an approach has limited capacity, however, since oversized and 
agglomerated bedding material quickly clogs the pores of the screen 
necessitating an interruption of the separating process. While most 
bedding material would be expected to pass through screen openings of 
approximately 1/4 to 1/2 inch in size, the mechanical vibration of the 
screen used in an attempt to increase production tends to agglomerate the 
bedding material into larger particles. The result is that the bedding 
material is held on the upper surface of the screen together with the 
worms and the process must be stopped to perform this secondary separation 
of bedding material from worms. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a device for separating 
earthworms from bedding material and from worm castings on a high volume, 
continuous basis. 
The present invention is for an earthworm separating device comprising an 
endless belt fabricated from a screen having a mesh size having openings 
between 3/16 and 1/2 inches. The upper surface of the upper belt is 
designated the separating surface. The separating surface is held on an 
incline of between 1.degree. and 15.degree. with respect to the 
horizontal. The endless belt is driven in an upward direction with respect 
to the incline at a speed of between 0.5 and 5.0 feet per second and 
vibrating means are positioned near the lower end of the separating 
surface. 
A mixture of worms in bedding material is deposited on the upper surface of 
the separating surface and the worms are held on the separating surface 
whereas the worm castings and small size bedding material passes through 
the vibrating screen. The worms then pass upwardly and over the end of the 
endless screen and are thereby separated from the bedding material and 
castings. The worm castings pass through the separating surface and are 
collected for use as a plant nutrient. A portion of the bedding material 
tends to be "balled up" by the vibrating action of the moving screen and, 
because of the incline, rolls downwardly and at the opposite end of the 
moving screen or belt from the end over which the worms are removed. The 
initial worms and bedding are thus separated into three distinct groupings 
namely worms, worm castings also containing bedding fines and agglomerated 
worm bedding.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The mechanical earthworm harvester is supported on a frame 10 which has a 
pair of adjustable legs 11 for adjusting the horizontal incline of the 
harvester. Because of the different consistency of various bedding 
materials it is appropriate that the angle of inclination of the 
separating surface be adjustable over a relatively wide range and a pair 
of tightening screws 12 and 13 hold the frame in any desired degree of 
inclination. A motor and gear box 14 is mounted on frame 10 and provides 
all the mechanical drive and source of vibration necessary for operation 
of the harvester. A first belt 15 passes over a pulley 16 which drives the 
central shaft 17 to which pulley 18 is affixed. Pulley 17 drives the 
second belt 18a which passes over a pulley 19 which is also shown in end 
view in FIG. 3. Pulley 19 drives a shaft 20 to which three wheels 21, 22 
and 23 are affixed. A second belt 18a and pulley 19' are also driven by 
shaft 17 in a manner analogous to that described for belt 18 and pulley 
19. 
The endless belt or screen 25 passes over the exterior surface of three 
wheels 21 through 23 and over a similar set of idler wheels at the other 
end of the screen 25. These wheels are held on shaft 26 which is in turn, 
held in a moveable bearing provided with adjustment means 27 for adjusting 
the tension of the belt. The upper surface of belt 25 comprises the 
separating surface. Vibrating means, indicated generally by reference 
character 30 provides the necessary vibration for the separator surface. 
The vibration is brought about by an eccentric shaft which is welded to 
shaft 24 which is rotated by pulley 31' which is turned by belt 31. Shaft 
24 has an outside diameter of 1/2 inch and a flat portion 1/8 inch in 
depth is milled from the surface of the shaft for a distance of one inch 
from the inner end. An eccentric shaft 28 also has a 1/2 inch diameter and 
a 1/8 inch flat portion milled from its surface for a distance of one inch 
on each end. The flat surface of shaft 24 is welded to the flat surface of 
shaft 28 at one end and to a corresponding shaft 24' (not shown). A pair 
of arms 32 and 32' (not shown) transmit this eccentric motion to upper 
frame 33 and thus to the separating surface of the screen or belt 25. 
It has been found that by locating the vibrator near the lower end of the 
separating surface, that the maximum amount of vibration occurs at a point 
when the worms are best protected by the bedding. As the bedding and 
castings are separated from the worms and the worms move upwardly along 
the belt the amount of vibration decreases thereby reducing damage to the 
worms. This vibrating action also tends to cause unused bedding material 
to be formed into balls which roll down the incline rather than being 
moved upwardly with the worms. 
In operation, the original worm tray 35 is placed on a support 36 and the 
worms, castings, and bedding are fed into a feeder screen 37 which is made 
of a larger mesh screen than screen 25. Typically the moving screen or 
belt should have an opening sizes of about 3/16 and 1/2 inches and 
preferably about 1/4 inch in size whereas the feeder screen should 
preferably have an opening size of from about 3/8 to 3/4 inches preferably 
about 1/2 inch. Feeder screen 37 is also vibrated and any over-sized 
material is removed from the upper surface of screen 37. Screen 37 
performs an initial breaking up or separation of the worm bedding and the 
partially separated material falls onto the separating surface upon which 
the final separation is made. 
As shown best in FIG. 2, the angle of incline "a" of the separating surface 
is set such that the bedding material moves down the incline and the worms 
are carried upwardly along the upper surface of screen 25. The proper 
angle of incline depends on the nature of bedding material, size of screen 
mesh, speed of belt movement and amount of vibration. It has been found 
that inclination angles between 1.degree. and 15.degree. are useful with 
5.degree. being average for most conditions. The castings indicated in 
FIG. 4 generally by reference character 40 pass through the separating 
screen 25 and may either be collected directly below the screen or may be 
permitted to fall through the returning moveable screen and collected on 
the ground. 
Gear box 14 has an output of 135 rpm and an output pulley of 4 inches 
diameter. This 4 inch output pulley passes over pulley 16 which is ten 
inches in diameter which turns a two inch pulley 18 at a speed of 33 3/4 
rpm. Pulley 18 is connected to belt 18a which turns pulley 19 and shaft 20 
at 27 rpm. The diameter of wheels 21 22, and 23 is ten inches and thus the 
separating surface moves at a rate of 1.2 feet per second. This speed 
permits the high volume harvesting of worm beds and production rates of up 
to 60 lbs. per hour have been obtained. This production rate was obtained 
with a separating surface approximately 61/2 feet in length and 2 feet in 
width and a screen opening size of 1/4 inch. Speeds between 0.3 and 5 ft. 
per second can be used with about 1 ft. per second being preferred. 
The vibrating shaft 24 is turned at a speed of 270 rpm, which has been 
found to provide ample vibration. Vibration rates between 100 and 500 
cycles per second are believed useful in the practice of the present 
invention. A pair of rubber liners 41 and 42 serve to transmit the 
vibration from frame 33 to the belt or screen 25. They also tend to hold 
the bedding and worms on the separating surface of screen 25. While the 
screen can be fabricated from any material having appropriate physical 
strength and corrosion resistance it has been found that galvanized wire 
is suitable for this use. 
The present embodiments of this invention are thus to be considered in all 
respects as illustrative and not restrictive, the scope of the invention 
being indicated by the appended claims rather than by the foregoing 
description. All changes which come within the meaning and range of 
equivalency of the claims therefore are intended to be embraced therein.