CIRCULAR 61
(Reprinted 1937) AUGUST 1932(Reprinted 
An Inexpensive Machine for Filling
The Trench Silo
By
ELLIS G. DISEKER
AGRICULTURAL EXPERIMENT STATION
OF THE
ALABAMA POLYTECHNIC INSTITUTE
M. J. FUNCHESS, Director
AUBURN
Contents
COST OF BUILDING THE TRENCH SILO ------- - -
SMALL POWER FEED CUTTER 4------------------- -4
TEST OF FEED CUTTER FOR FILLING THE TRENCH SILO 4
CARE OF THE CUTTER 5-----------------------------------------
SPEED OF THE CUTTER ------------------------------ 6
REMOVING SILAGE FROM THE TRENCH 6--------------------------
SUMMARY--------------------------------------------------- 7
An lnxpensive iMachine for Filling the
T1rench Silo
As-zi ~tant ai_'Vkjcu1a n zine i
SILAGEF 
is an excellent 
feed( fori 
beef ndh 
dairi- attle. 
It is
S sp~ecially Valualile (loving the dri- tall and Wxintier months
when piasturage andI nther green leeds are lnot ax ailalie.
In the past the use of silIage has been limited I ec ause of the
expensive eq uip~ment econsid ered necessary- for its prod1uction.
The man wxith only a fexx nx cows cold not affordI the necessary-
coist of construlcting a x ertiecal silo of co enet e ho~illw tile, or
*wood, and of sec uring, a sih1 ige c ntter and the pnoxwer xxiih xwhich
to op~erate it; hnxxexei. sinee the dexvelopment of the trenceh silo.
as dlest ibedl in Alabama Lxperiimenlt Station Circular 59, and
the machine tor fillingO it. (deserilled iln this pl)icaition. .5ila2e
* ma Ise proi\ ilid folr (x elti a small 111rd at ai nomllinal cos't.
Cost of Building the Trench Silo.-Ver}- little i'ad ahot
Ia , is Ilec 'sal'x to ltiili a trenceh silo. Thiere ale seasons11 ot the
*year wxheni mni andt mules ale idle on practicallV eve(y- tfrm
laborI at such a season should eost x (IV little. The tools lleees-
sary' are a turllonx piek. sihoxvel. and slip scel' all of wxhich
ale found ion the ax elage tarm. with the eseeltin of the slip
serape. A slip selaple ean Ie bought row alniut * 12 andl it ean lbe
used late ci or terracing an V1xarious (idl jiobs around the farm.
F F.-
I lli lII , .riu" how the machiuc 
aud enCine should he l waced.
feed (Litter use tor cutthm sou m sjluigze A' the trench siO.
Even if a reasonable w\age is charged for man- aind mule-labor.
the coust o1t dlitging' a 50-toll silui shouldl not escil X20 to S25
Small Power Feed Cutter.-A small feed cull t (. without at
bulowe r, whIiichb may be p urchasedl tor a bout $W4. \\ tested dur-
ing the fall of 1931. This machine has sufficient capacity for
filling a trench silo anid requires o nly a smal11 amon nt of1 pow~er.
If a tractor is not available. a small gas engine is sufficient for
its operation. The cutlte Ciwas motunted on legs instead ot wheels.
It was nec essary- to anc hor andI brac e the mac hine, as sh owxn in
Figure 1. in order to heel) the diving belt runni ng tight. The
small gas engine used for op~erating the cutter w\as also placedi
on a plattorm and anchbored.
The machine has four 11-inch curved knives which can be
easily reptlacedl and are quickly adj ustabl)1e. Various lengths of
silage ca~n be obtained by adj ustment of the feed r'oll ers. Tbe
cane is fed into the cutter by hand and the feed rollers carry
the cane over a steel shearing bar wvhere it is cut into short
lengths by the rex ol\ ing knives'.
Test of Feed Cutter for Filling the Trench Silo.-This feed
Cutter wXas teat({ lir culting soghum cane. The cutler wxas
placed beside the s ilo and the silIage tel into the trench1 when
cut. The results of the cap~acity tests wvith three (different sources
of power~i are showvn in Table 1.
The cutter req ui red 3.83 horse power for cutting at maxi-
mum capacity as determined by the electrical cons-umption. It
was concluded that a -h orse- 10 X er engline wxitht a 1 6-inch-di-
ainetet' pulley running at a speed of 400 reo-olutiois perT minute
would supplly ample towvel for the fuill operating capacity of the
cutter without overloading the engine. Bly usin g an engine with
TABLE I.-The Capacity of the Small Power Feed Cutter Using Different
Sources of Powter at Various Speeds.
S 'u ce
of
Power 1
15-30 H P'
tracetor(
3 II P
gas engine
5 11 P
elect tic
mo10tor
of
pulley
16.5
1t)
4I.5
Utner
Speed
i PAIi
('ltterI
Sp1eed
R 1' 51
in tonls
per hour
1n(1
425
1,7140
Nt:A 12-inch puilley -, use oQ, the fodii~r
-*'his ing rit> was caid iy slipipagie o the Lol di rm ihe smill, 
high- ipieiipalley
these specifications anti feeding the cutter 
to its m-axinmum ca-
pacity. it is ptossihble to cut 0( tons of silagve 
in tenl ho~urs. HIowt-
ever, it is exc eedingI lifificult fui' onle mian to 14reed 
this mac hime
to its maximum capacity- because (If the stmill 
opening througrh
which the caine is ted.
Care of the Cut-
ter.-lhis I~n vi' 
f
mac hinett is ge neral-
Iy ,veaker in con-
struiction than tht
heavier cutters 
de-
signed for large'
units of power' andi
high sipeedi. M\ori
care. therefore, 
i-
req uired in its op-
erattion(I to ob~tin 
its
maximum life 011(1
efficiency. The cut-
ter' shouild lbe oiled
abotut e ei'v hour
with heat \' mote
oil ohr its ('LOuiN ,-
lent. Oiling- can 
1w
done wiiithout stoll-
ping the cutter anfd
-vill take only :
few secondsl. i
ease the flahhi
hear'ings are dlaml-
aged fronm over-
speeding. excessive
grit. or' lack of oil.
I 
>.
1;i, l
Station latili.
they can be poured at any blacksmith shop or garage. This,
however, may happen when time is very valuable and can 
be
avoided by careful attention to lubrication. It is advisable 
to
always check the alignment of the knives and tighten 
or re-
adjust loose bolts, bearings, etc., after using the cutter 
so that it
will be in first-class condition for the next job. 
When the ma-
chine is stored all metal parts should be oiled thoroughly 
or cov-
ered with grease and the machine placed in a dry shed to prevent
rusting and warping of the apron.
Speed of the Cutter.-Where ample power is available, there
is a tendency to run a machine much faster than the speed for
which it was designed. This is not only dangerous and 
consti-
tues a waste of power but results in shortening the life of the
machine. In the tests the maximum amount of silage was ob-
tained when the cutter was running at a speed of 550 revolu-
tions per minute. When driven at a greater speed, vibration of
the cutter was quite noticeable. It was considered that this was
the maximum speed for this machine.
It is a rather simple matter to figure the size of a pulley for
any desired speed. If one knows the speed of the engine, the
desired speed of the cutter, and the size of the pulley on either
the engine or cutter, the size of the other pulley can be calcu-
lated from the following formula.
dXr-DXR
where d = diameter of pulley of driver
r = revolutions per minute of the driver
D - the diameter of the pulley of the driven
R = the revolutions per minute of the driven
For example, if a tractor or gas engine, which has a 
pulley 11
inches in diameter, is running at a speed of 600 revolutions 
per
minute, what size pulley is required on the cutter to run it at
550 revolutions per minute?
Substituting in the formula:
600 X 11 = D X 550
6600 550D
6600
D - 50 12"
550
D -= 12 inches, diameter of pulley for cutter.
Removing Silage from the Trench.-In some instances the
trench silo may be located at a considerable distance from 
the
barn and, since silage is rather heavy and bulky, it will 
become
burdensome to carry it in baskets or tubs. In such cases a 
track
and feed carrier may be installed or a two-wheel cart 
with
shafts can be made with little expense. Wheels for 
the cart can
be found at most garages or junk piles, and a box or bed 
of the
desired size can be bolted on the axle and properly braced.
7
Homemade shafts and singletrees can be made from poles. This
cart can be backed into the trench by a mule or horse and silage
easily moved to the feeding troughs.
SUMMARY
The cost of ensilage may be kept low if a trench silo and a
small feed cutter are used. The cost of digging a 50-ton trench
silo should not exceed $25. A small feed cutter with sufficient
capacity for filling the silo may be obtained for about $30. A
blower is not necessary.
Tests showed that a 4-horse-power gasoline engine furnished
ample power to operate this machine at its maximum capacity
of 40 tons of ensilage per day. Suggestions for operation and
care of this machine are included.