2001/08/13 Caterpillar

Backhoe Loader:

416D (S/N: BFP1-UP; BGJ1-UP; BKG1-UP)

420D (S/N: BKC1-UP; BLN1-UP; BMC1-UP; FDP1-UP)

424D (S/N: BGP1-UP; BKR1-UP)

428D (S/N: BLL1-UP; BMT1-UP; BNB1-UP; BNS1-UP)

430D (S/N: BML1-UP; BNK1-UP)

432D (S/N: BLD1-UP)

438D (S/N: BPE1-UP; BPN1-UP)

442D (S/N: BRG1-UP; BRY1-UP)

Reference: Special Instruction, REHS0934-00, February 2001, "Installing the Bucket Teeth of the Diagonal Retention System"

The Diagonal Retention System

Illustration 1	g00815490
The Diagonal Retention System (1) Tip Adapter (2) Tip (3) Flex Pin

The Diagonal Retention System offers an improved system for the retention of bucket teeth. The tip adapters (1) are welded onto the base edge of the bucket. The tips (2) are attached to the tip adapters with flex pins (3). See Illustration 1.

Correct installation of the flex pins is essential for the diagonal retention system to work. Instructions for the installation and removal of the flex pins are provided in this article.

All of the components of the Diagonal Retention System are identified in Table 1.

Installing the Flex Pin

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Illustration 2	g00815664

1. Place the tip on the tip adapter. The curvature of the tip should correspond to the curvature of the bucket. See Illustration 2.

   Note: The hole in the tip and the hole in the tip adapter will be offset.

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Illustration 3	g00815680
The Flex Pin (A) Front of the flex pin (B) Rubber core (C) Back of the flex pin

2. Orient a new flex pin (3) with the groove toward the front of the tip. The word "BACK", which is stamped into the back of the flex pin, must be toward the rear of the tip. See Illustration 3.

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Illustration 4	g00815669

3. Use a pair of locking pliers to compress the end of the flex pin that will be inserted in the tip. See Illustration 4.

   Note: Grasp the flex pin with the locking pliers slightly below the center of the flex pin.

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Illustration 5	g00815675

4. Insert the end of the pin that has been compressed into the hole in the tip. See Illustration 5.

5. Use a hammer and strike the end of the flex pin firmly in order to drive the flex pin in the hole.

6. Drive the flex pin into the hole until the locking pliers contact the tip.

   Reference: Product Safety, SENR7733, "Important Safety Information". "Wear protective glasses when pounding on any part of the product or its work tool with a hammer or sledge".

7. Release the pliers and remove the pliers from the flex pin.

8. Drive the flex pin into the hole until the flex pin is flush with the surface of the tip.

9. Examine both ends of the flex pin in order to determine if the flex pin is correctly seated. Each end of the flex pin should be positioned in the same manner with respect to the surface of the tip.

   Note: To test for correct locking, place a punch on one end of the flex pin. Use a punch with sufficient diameter so that the end of the punch will contact both halves of the flex pin. Use a hammer and tap lightly on the punch. You should be able to feel the resistance from the locking tab.

10. Check the condition of the flex pin. See Table 2.
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    Table 2

    Checks of the Condition of Flex Pin After Installation
    The rubber core is highly compressed and/or the rubber protrudes from the sides of the steel halves.	Acceptable	No action is required.
    The rubber core is cut and/or torn by the pin hole in the tip.	Acceptable	No action is required.
    The rubber core is unbonded from the steel halves. (1)	Unacceptable	Replace the flex pin with a new flex pin.

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    ( 1 )

    This may result in loss of the pin and the tip during operation.

Removing the Flex Pin

1. Select a punch with a diameter that is slightly smaller than the flex pin.

2. Position the punch on one end of the flex pin and tilt the punch slightly toward the front of the tip.

   Note: Tilting the punch toward the front of the tip will enable the punch to move the front half of the flex pin backward before the punch contacts the back half of the flex pin. This action will unseat the locking tab.

3. Strike the punch sharply with a hammer in order to unseat the locking tab.

4. Once the locking tab has been unseated, continue to drive the flex pin out of the hole.

5. Discard the flex pin.

   Note: With the Diagonal Retention System, the flex pin must be replaced when the tip is replaced. The rubber core of the flex pin deteriorates with use. In order to ensure the proper retention of tips, it is critical that a flex pin is never reused.