McCormick-Deering Potato Digger



McCormick-Deering Potato Digger

This material is taken directly from the manufacturer’s original operating and setup instructions, a booklet given to the new owners of this implement when first purchased. It is written as though you are opening the crate and assembling your digger. You are most likely not. But that doesn’t mean you can’t use this information to good advantage as you work to understand, restore, and use your good machine. LRM

Instructions for Setting Up
Remove all wires and arrange parts conveniently.
Oil all bearings and moving parts as you proceed and see that they work freely.
Bolts must be used in holes in which they are found, or in parts to which they are attached, unless otherwise shown.
The illustrations show parts to be assembled; these must be placed on the machine in the order numbered.
In the following instructions, wherever the terms “left” and “right” are used, it should be understood to mean from a position behind and facing the machine.


1. Connect shovel lifting beam (7038AA).
2. Secure connecting links.
3. Secure truck wheels to axles, placing a steel washer at each end of wheel hub.
4. Secure tongue, hammer strap and clevis to truck frame, placing the distance block below the channel.
5. Secure truck axle braces to truck frame and to tongue.
6. Bolt tiller link connections to arms of shovel lifting beam so that truck wheels will be parallel to tongue.


1. Bolt lugs to tire.
2. Bolt seat to seat support
3. Bolt hinges (7255A right and 7256AA left for rod link elevator or 7280A right and 7281A left for riddle type elevators) to main drive shaft bracket. Put bolts in place from the inside with retaining clip (7277A) and nut on the outside.
1. Secure vine turner rods and fender rod as shown. (See illustration. No. 3.)


2. Raise rear shaker to place and secure hinges to lower channels. (See illustration No. 3.) The rear bolts take shaker frame hanger, front.
3. Put tilting rods to place.
4. Put on vine turner crank drive chain.
5. Attach pitman shield, right.
6. Put on shaker drive chain.
7. Attach shaker drive chain shield.
8. Secure oil can holder to tool box. Bolt tool box to main frame beam, left. (See illustration No. 5.)



(Rod Link Type Only)

Bolt hinges to main drive shaft brackets. (See item 3, illustration No. 2.)
1. Raise extension elevator in place and bolt hinges to sides.
2. Fasten tilting rods into place and attach lifting spring.
3. Place drive chain over sprockets and adjust chain tightener.
IMPORTANT: Place chain on sprockets with hooks forward and slot side out, to run in direction of travel, as shown in illustration No. 7A.



To detach chain, bend to coupling position and strike light blows.
4. Fasten elevator side extensions, or potato deflectors, in place.
The stone deflectors are adjustable by means of slot provided in them. In order that the deflectors may function properly and do the best work to cam the stones outwardly, loosen bolts at slots and adjust the deflectors so the lower face rubs slightly against the chain.
Important: Clevis should not be left loose on tractor draw bar. Use washers provided and draw up with nut until snug, then lock the cotter.






Continuous Apron Attachment
7076A—Only enough elevator speed and agitation should be used to obtain good separation. Plain rollers should be used when soil conditions will permit, as the extra wide elevator gives greater amount of separation which lessens the amount of agitation required.
7704A—Slip sprocket. Should be used when extension elevator drive chain is used, to allow for slippage of elevator apron.
7065AA—Should be used when slight agitation is required.
7064AA—Should be used when medium agitation is required.
7373AA—Should be used when violent agitation is required
(See illustration No. 14.)

1. Disconnect both main and extension elevator aprons and attach aprons at upper side. Remove enough links (about eight) so that apron does not drag on the ground, and connect aprons at lower side as illustrated.
Note: Look for open link which is beveled at both ends.
2. Fasten support roller, complete, to lower sides of extension elevator.
3. Bolt rollers to extension elevator sides.
4. Remove agitators from tie rod and replace with rollers.
5. Remove the regular apron drive sprockets and replace with special sprockets.
Use nothing but high-grade machine oil or high-grade hard grease.
Oil frequently, particularly during the first few days, with a new machine. As a general rule, frequent use of small quantities of oil gives better results than large quantities used at longer intervals. Be sure the oil holes are free from paint or dirt and see that the oil gets down into the bearings.
It is well to throw the machine into gear and drive it around for a time before starting to dig. This not only loosens up the parts and works the oil down into the bearings, but affords the operator an opportunity to see the parts in motion and to become familiar with the various parts and their functions.
All bearings or moving parts are provided with Alemite hydraulic fittings and require oil regularly.
Do not use oil or grease on the bearings for elevator apron rollers or agitators.


Before starting the digger, thoroughly clean all the paint or varnish from the shovel. This is important.
The digger is thrown into gear or out of gear by means of the lever at the right hand side of the driver’s seat. This lever also regulates the position of the rear shaker and vine turner or extension elevator. When the lever is in the highest notch of the quadrant the machine is out of gear.
The pawl shifter lever links are adjustable and should be set at such a length that the pawls will be entirely out of engagement when the lever is in the highest notch in the quadrant, and will be fully engaged when the machine is thrown in gear.
The depth the shovel enters the ground is regulated by the adjusting straps on the lifting lever quadrant. The lifting lever is of the pump type and may be set to the most convenient position on the quadrant. The ease with which the shovel can be raised depends on the will of the operator, as there are four holes in the quadrant for adjustment of the straps.

Adjustment of Aprons
Aprons may be adjusted by adding or removing link.
As apron wears, links may be removed by disconnecting apron at open link, which is beveled at both ends, and removing links until apron clears ground. (See “1,” illustration No. 14.)
If too many links are removed, it will make the apron too tight. This will cause digger to run hard and cause catching of small stones at front end of apron.
In some stony conditions, it is advisable to set elevator lower rollers in the same position as when stone trap is used (illustration No. 20), but leaving the space taken by stone trap open. This allows small stones to pass around lower rolls and gives room for slack apron to go ahead without catching on shovel.
Where agitation is required, the agitators shipped with the Digger may be substituted for plain rollers and may be varied to suit conditions by moving them up or down on the elevator.
When the lower agitator is moved farther up the elevator, the position of the supporting roller underneath the chain should be changed correspondingly to prevent stones locking between roller and agitator. (See Illustration No. 17.)
Stone Deflectors and Flanged Rollers may be obtained through repairs. The Stone Deflectors are adjustable by means of slot provided in them. In order that the deflectors may function properly and do the best work to cam the stones outwardly, loosen bolts at slots and adjust the deflectors so the lower face rubs slightly against the chain.

(See Illustration No. 19.)
When the nature of the soil is such that no agitation of the elevator is desired or needed, the grate may be raised up and supported in a stationary position by means of two flat support (A) resting on axle.

(6-Ft. or 7-Ft.)
The position of the rear shaker and vine turner must be governed by conditions. The best results in rowing the potatoes, however, will be obtained by having the center shaker rods just touch the ground when the machine is set in a working position.
The vine turner fork crank is assembled in the upper holes in the bracket when the machine is sent out. A lower set of holes is provided and the crank should be used in the position where best work can be done under existing conditions.
The shaker pitman crank and shaker crankshaft sprocket have two holes for pitman crank pin, one hole giving 2 1/8-inch throw, the other, 2 ½-inch throw.