Henry
P. Cole Larry
R. Piercy
University of Kentucky
Instructor's
Guide and Activity Materials Table of Contents
All the
materials needed for this activity are inexpensive, readily
available, easily assembled, and once prepared can be used
repeatedly with little effort and preparation time. However,
about three or four hours are needed to gather and assemble
the materials the first time. These instructions are broken
into three parts. These include (a) obtaining and preparing
the model tractor(s) with and without a ROPS, (b) constructing
the cardboard(or 1/4 inch plywood if one wishes) bridge and
ramp needed for the demonstration, and (c)gathering the other
materials needed to complete the activity. Follow these steps
to gather and assemble the materials needed for the activity.
Note that the construction, preparation,and use of these materials
is a good project for vocational agriculture students.
Either
one or two model tractors can be used for the activity.
If one model tractor issued it must come without a ROPS
and a model ROPS for the tractor must be constructed to
retrofit the model tractor. If two model tractors are used,
one must come without a ROPS and the other already fitted
with a ROPS. Directions for both alternatives are provided.
1.
Obtain a 1/16th scale model farm tractor without a ROPS.
These are available from tractor equipment dealers and farm
supply stores for about $30. (Many farm safety instructors
already have model tractors.) Make sure the real tractor
that the model represents has a ROPS retrofit package available.
(You don't want to convey false information to the participants.)
Also make sure the scale model tractor you purchase has
sufficient space on the rear axle between the tractor fenders
and the tractor body to fit a small clamp (see
Figure 1). Check to make sure that the seat is back
far enough from the steering wheel that a medium size hen's
egg can be placed in the seat (see Figure 2).
A
1/16th scale model of an International Fat-mall 856 works
well because (a) there is1/ 2 inch of space on the rear
axle housing between the tractor fender and the tractor
body, (b) the seat is large enough and back far enough from
the steering wheel to accommodate even a large hen's egg,
(c) the seat is large enough to attach two Velcro sticky
back squares, one on the seat bottom and the other on the
upright seat back, and(d) a retrofit ROPS package is available
for actual Farmal 856 tractors. The instructions and drawings
that follow explain how to construct a ROPS for this 1/16th
inch scale tractor. If you use another tractor scale model,
you will need to adjust the specifications given in Figures
1 - 9.
NOTE:
An easier alternative is to obtain two similar size 1/16th
scale model tractors,one that comes equipped with a ROPS
and one that does not. Both tractors must have a seat and
operator's compartment large enough to seat a medium sized
hen's egg. In this case two tractors are used to conduct
the demonstration, one without a ROPS for the first demonstration,
the second tractor with the ROPS and the unbelted Mr. Good
Egg farmer for the second demonstrations, and the same ROPS-equipped
model tractor with the belted egg operator for the third
demonstration. If you choose this alternative, skip instructions
2 through 6 and go to the Constructing the Cardboard Bridge
section (item 8).
2.
If you decide to use one model tractor and a retrofit
model ROPS, attach two 1/2 inch diameter vinyl coated steel
wire harness clamps to the model tractor rear axle, placing
each clamp between the fender and the tractor body as shown
in Figure 3. These clamps can be purchased
in nearly any automotive, hardware, or electrical supply
store.
3.
Obtain a 1/4 inch diameter steel rod 14.5 inches long.
Using a tap and die set, thread one inch of both ends of
the rod. Use a 1/4 inch x 20 threads per inch die
(see Figure 4).
4.
Make two marks on the same side of the steel rod 5
1/2 inches from each end. Place one end of the steel rod
upright in a vice. Heat the rod with a torch at the 5 1/2
inchmark and bend the rod inward to achieve a 90 degree
angle. Repeat the procedure for the other end of the rod.
Bend the rod to the dimensions listed in Figure
5. Be careful to make the bends 90 degrees each and
in the same plane to keep the upright portions of the two
sides parallel in both planes. If it is bent properly, when
it is laid down the U-shaped rod should lie flat on the workbench
or table top. If you don't have a torch to heat the rod,
notch the inside bend of the rod with a triangular file
at the two marks 5 1/2 inches from each end of the rod.
Then bend each 6 inch end of the rod to a 90 degree angle
using a vice to hold the 6 inch upright portion close to
the notch. Then bend and tap the rod with a ball peen hammer
until a fairly tight rounded bend brings the top portion
of the ROPS to a 90 degree angle with the 6 inch upright
side. Repeat the process for the other side. Again, be careful
to keep the upright portions of the two sides of the bent
rod parallel in both planes.
5.
Place one 1/4 inch nut on each end of the model ROPS
you have just constructed. Screw each nut all the way up
to the end of the threads on each side of the rod and tighten
finger tight. (These two nuts act as spacers that keep the
rod from falling through the holes in the clamp.) see
Figure 6.
6.
Place the ends of the model ROPS through the holes
in the clamps (see Figure 7). Add a second
1/4 inch nut to each side of the model ROPS (see
Figure 8.) Then tighten the nuts slightly and adjust
the angle of the ROPS to the proper position by tilting
it back or forward as needed (see Figure 8).
Then tighten the second nuts sufficiently to hold the clamps
on the axle in place. Finger tight is usually sufficient
to hold the model ROPS firmly in place, especially if vinyl
coated clamps are used. Otherwise a small socket wrench
with a screwdriver handle works well.
7.
Remove the model ROPS. Paint the unthreaded portion
with a flat black paint. Don't paint the threaded ends (see
Figure 5). Allow the paint to dry and then reinstall
the ROPS on the model tractor.
8. Constructing the cardboard bridge is the next step.
First, find a large heavy corrugated cardboard box. Look
at Figures 10 - 13 and follow these instructions
-
Use a retractable blade knife and a straight edge to cut
a rectangular piece of cardboard about 14 inches wide
x 44 inches long.
-
The 34 inch section of the bridge needs to be one-piece
of cardboard with no folds.The 10 inch ramp with its fold
can be cut from the cardboard box at the end of the box
where the cardboard is folded upward. Leave the 10 inch
ramp attached to the main part of the cardboard bridge
(see Figure 10).
-
Using a retractable knife and a straight edge, cut a rectangle
16 inches long by 6 inches wide in the side of the 34
inch long cardboard bridge as shown in Figure
10. Cut the two 6 inch ends of this flap all the way
through. Cut the 16 inch side of the rectangle from the
top side and cut only the top layer of the cardboard leaving
the lower layer as a hinge. When you have made this cut,
fold the 16 inch long flapdown.
9.
Making the bridge supports is the next step. Cut two 12 inch
sections and one 30 inch section from a 2 x 4 inch stud or
use scrap. Place the pieces of 2 x 4s on a large tabletop
or the floor as shown in Figure 11. Make
one more 5 inch long section of 2 x 4.Attach a 2 foot length
of string to one end of the block by using a screw or a nail,
or by drilling a hole through one end of the block.
10.
Place the cardboard bridge and ramp on top of the 2 x 4
supports as shown in Figure12. You are
almost ready to do the demonstration.
11.
Place the 5 inch section of 2 x 4 with the string attached
to it under the 16 inch hinged section of the bridge as
shown in Figure 13. This section of the
bridge simulates an embankment failure when the block is
pulled out from under the cardboard flap.
12.
Before you conduct the activity, test your apparatus. Set
a model tractor on the bridge as shown in Figure
13. Then roll the tractor slowly onto the cardboard
flap. When the rear wheel of the tractor is 2 inches out
on the flap, pull the 5 inch supporting blockout and away
from the bridge. The tractor should overturn sideways with
enough force to crush a Mr. Good Egg farmer who is not protected
by a ROPS and seat belt.
13.
Purchase a package or two of Velcro Sticky Back Squares,
hook and loop fasteners. These are two-part 7/8 inch squares
used to hold picture frames or other objects against a wall
or some other surface. These fasteners can be purchased
at a supermarket, hardware store, or in the home or hardware
section of a general merchandise store. The Velcro sticky
fasteners are used to hold the "belted" Mr. Good Egg farmer
to the ROPS-equipped model tractor seat.
14.
It's a good idea to have a roll of Scotch or masking
tape. A strip of tape can be placed on the underside of
the bridge to reinforce the hinge on the cardboard flap.
Another piece of tape can be used to tape the lower end
of the ramp to the table top or to the floor.
15.
Obtain five or six different color felt pens. The pens are
used to draw faces on the Mr.Good Egg farmers. These can
be purchased in any drug store, supermarket, or general
merchandise store.
16.
Purchase a dozen raw, medium size hen's eggs from a grocery
store or supermarket.
17.
Obtain a 4 x 6 foot or larger sheet of clear plastic. The
plastic sheet is taped to a large table top or to the floor
to protect the surface from broken egg white and yolk. Clear
plastic sheets are available from scrap wrapping, from hardware
stores, farm or construction supply stores.
18.
Have a roll of paper towels, a sponge, a bucket of
water, and a spray bottle of countertop cleaner handy. These
are used to clean up egg white and yolk form crushed Mr.
Good Egg farmers who had the misfortune of overturning a
model tractor that was not fitted with a ROPS, and/or who
were on a ROPS-equipped tractor but who were not wearing
a seat belt during the overturn.
The
six pages of figures that follow illustrate how to select
a model tractor for the Mr.Good Egg activity, and how to
fit this tractor with a model ROPS. Other diagrams also
illustrate how to construct the cardboard bridge with it
ramp and break-away embankment.
Figure
1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 10
Figure 11
Figure 12
Figure 13
|
