Balance Wheel

The balance wheel (figures 4-6 [R] and 4-11 [N]) transfers the motion and power from the onethird-horsepower electric motor to the arm shaft. To remove the balance wheel, you must first loosen the two setscrews attaching it to the arm shaft; then you withdraw it from the machine.

NOTE: The balance wheel is very fragile. Do not hit it with a hammer to remove it.

Arm Shaft Connection Belt

The arm shaft connection belt (figure 4-4 [A]) transfers the power and motion from the arm shaft connection belt pulley to the safety clutch pulley. To remove the arm shaft connection belt, you insert a small screwdriver along the left edge and slide the belt from the safety clutch pulley.

Arm Shaft Connection Belt Pulley Position Screw

The arm shaft connection belt pulley position screw holds the pulley in a freed position. The arm shaft connection belt pulley position screw is the larger of the two screws on the pulley. The smaller screw is a setscrew. It must be loosened but not removed from the pulley. Remove the arm shaft connection belt pulley position screw by unscrewing it.

NOTE: For machines with ball bearings, the arm shaft arm bushing setscrews are located just to the right of the connection belt pulley. They secure the arm shaft bushing to the arm shaft. These screws are not removed from the bushing; however, they must be loosened for the arm shaft to be removed.

The Presser-Lifting Eccentric

The presser-lifting eccentric supplies the lift for the alternating presser feet. Free the presser-lifting eccentric by loosening the two presser-lifting eccentric setscrews located through the opening in the rear of the arm (figure 4-11 [A]). You must rotate the balance wheel to loosen the second screw. Be sure the eccentric rotates freely on the shaft.

Feed Indicator Disc

The feed indicator disc shows the operator the number of stitches per inch the machine is sewing. It also allows the operator to set the machine to sew a desired number of stitches per inch. Loosen the feed indicator disc setscrew and ensure the disc will rotate freely on the shaft.

Needlebar Crank

The needlebar crank transfers the motion and power from the arm shaft to the needlebar by the needlebar driving stud. Do not remove the needlebar crank from the arm shaft.

Needlebar Connecting Link Stud

The needlebar connecting link stud transfers the motion and power from the needlebar crank to the needlebar connecting link. Do not remove the needlebar connecting link stud from the arm shaft.

Needlebar Crank Friction Washer

The needlebar crank friction washer acts as a bearing surface between the needlebar crank and the front arm shaft bushing. In some cases the needlebar crank friction washer remains with the machine upon removal of the arm shaft bushing. If this occurs, insert the index finger in the arm shaft recess and remove the washer.

NOTE: The operator must be especially careful when assembling the machine to be certain the needlebar crank friction washer is returned to the arm shaft. Absence of the needlebar crank friction washer will cause the machine to bind.

Arm Shaft

The arm shaft (figure 4-11 [0]) acts as a carrier for, and transfers the power and motion to, the arm shaft connection belt pulley, the feed indicator disc, the needlebar crank friction washer, and the needlebar crank. To remove the arm shaft, grasp it with the left hand and withdraw it from the face of the machine.

Right- and Left-Hand Bed Slide Plates

The bed slide plates allow for inspection and maintenance of the bobbin assembly. The righthand bed slide has a cutout on the bottom side. This cutout allows the needle thread to pass over the bobbin case without jamming.

Throat Plate

The throat plate acts as a guide for the feed dog and provides a firm foundation over which the material may flow while the stitch is being made. The throat plate does not need to be removed from the machine.

Needlebar Rock Frame Rockshaft

The needlebar rock frame rockshaft carries the feeding motion and power from the feeding mechanism in the bed of the machine to the needlebar rock frame. To remove the needlebar rock frame rockshaft, you insert the screwdriver in the opening in the rear of the uprise and loosen the needlebar rock frame rockshaft crank pinch screw. Remove the needlebar rock frame rockshaft from the face of the machine.

Needlebar Rock Frame Rockshaft Crank and Connection

The needlebar rock frame rockshaft crank and connection transfers the feeding motion and power from the feed-driving rockshaft crank to the needlebar rock frame rockshaft. To remove the needlebar rock frame rockshaft crank and connection, you loosen the pinch screw at the feed-driving rockshaft crank (figure 4-6 [G]). Then you grasp the feed-driving rockshaft crank (figure 4-6 [H]), slide it to the right to remove it from the feed-driving rockshaft, and withdraw it from the machine. In so doing, the needlebar rock frame rockshaft crank and connection parts are also removed. The parts removed remain as an assembly.

Feed-Driving Rockshaft Crank

The feed-driving rockshaft crank transfers the feeding motion of the feed-driving rockshaft to the needlebar rock frame rockshaft crank and connection. The feed-driving rockshaft crank is removed simultaneously with the needlebar rock frame rockshaft crank and connection.

Feed-Lifting Cam Fork

The feed-lifting cam fork gives the feed dog its up and down motion during the feeding operation. To remove the feed-lifting cam fork, you unscrew the feed-lifting cam fork screw (figure 4-6 [E]), tilt the fork toward the operator, and withdraw it.

Feed-Driving Rockshaft

The feed-driving rockshaft (figure 4-6 [L]) coordinates the feeding motion of the feed dog and the feeding of the needle. To remove the feeddriving rockshaft, proceed in the following manner (refer to figure 4-6): . Loosen the hook saddle adjusting screw (figure 4-6 [B]). 

. Loosen the hook saddle pinch screw (figure 4-6 [A]). 

. Slide the hook saddle to the right as far as possible. 

. Loosen the feed-driving rockshaft crank pinch screw (figure 4-6 [G]). 

. Loosen the setscrews on each of the feeddriving rockshaft stop collars (figure 4-6 [M]). l Lift the feed bar toward the operator until it reaches a stop position. Move the bar to the left until it strikes the bed of the machine. Lift the bar upward to clear the bed of the machine and continue moving it to the left until the right end of the shaft reaches the feed-driving crank; this action forces the right feed-driving rockshaft stop collar from the rockshaft. Continue moving the rockshaft to the left until it clears the left stop collar. Withdraw the rockshaft from the machine.

Feed-Driving Rockshaft Stop Collars

The feed-driving rockshaft stop collars and setscrews (figure 4-6 [M]) act as retainers on each end of the feed-driving rockshaft to prevent any side-to-side play. The feed-driving rockshaft stop collars are removed in conjunction with the feed-driving rockshaft.

Feed Bar

The feed bar (figure 4-6 [F]) transfers the power and motion from the feed-driving rockshaft to the feed dog.

Feed Dog

The feed dog aids the needle in feeding the material to the machine. It is attached to the feed bar l

Hook-Driving Shaft and Attached Parts

The removal of the hook-driving shaft (figure 4-6 [N]) begins with the loosening of the attached parts, starting from the right and working to the left. 

. Loosen the setscrew and the spline screw in the hook-driving shaft bearing collar. (See figure 4-6 [O].) 

. Loosen the two setscrews in the hookdriving shaft lock ratchet. (See figure 4-6 [P].)

NOTE: Machines fitted with cast iron bushings instead of ball bearings will have only one spline screw. 

. Loosen the spline screw and the setscrews in the feed-driving eccentric. (See figure 4-6 ([Q].) l Loosen the hook saddle pinch screw (figure 4-6 [A]). 

l Loosen the two setscrews in the hookdriving gear. 

. Loosen the spline screw in the feed-lifting eccentric (figure 4-6 [T]).

NOTE: After you loosen the spline screw and the setscrews, each part must rotate freely on the shaft.