Here is a step-by-step guide for the bucket assembly process.

1. Safety First

• Park on solid, level ground.

• Turn off the engine and relieve hydraulic pressure (move joysticks through all motions with the engine off).

• Use adequate supports. Do not rely on the hydraulic cylinders to hold the stick and linkage while you are between them. Use jack stands or cribbing if the linkage must be raised.

2. Required Tools & Parts

• New pins and bushings (if applicable).

• Heavy grease (Lithium complex or specified EP grease).

• Sledgehammer (8–16 lbs) or a hydraulic pin driver.

• Alignment bar (a tapered drift punch or a bar slightly smaller than the pin diameter).

• Crane or lifting device (to hold the bucket).

• Crowbar and measuring tape.

Step 1: Prepare the Linkage

1. Retract the stick so it is vertical or slightly angled for easy access.

2. Remove the old bucket (if present) by driving out the Arm-to-Bucket pin (top pin) and the Link-to-Bucket pin (lower pin).

3. Inspect the bushings in the stick, link, and bucket ears. If the bushings are worn, they must be pressed out and replaced before assembly.

Step 2: Align the Bucket

This is the most time-consuming part. You need to align three components: the Stick (Arm), the Bucket, and the Link (H-Link or Power Link) .

1. Lift the bucket using a crane, forklift, or chains attached to the stick so that it sits directly under the stick’s mounting point.

2. Install the Arm Pin first (Top Pin):

   • Align the "ears" of the bucket with the eye of the stick.

   • Drive the alignment bar through one side to hold the weight.

   • Use a crowbar to tweak alignment until the main arm pin slides in by hand.

   • Grease the pin thoroughly before insertion.

   • Drive the pin flush with a sledgehammer if necessary, but avoid mushrooming the pin head.

   • Install retainers: Hitachi usually uses a bolt-on retainer plate or a snap ring on the arm pin. Torque bolts to manufacturer spec.

Step 3: Connect the Link (Linkage)

The linkage (often called the "H-link" or "dogbone") connects the bucket cylinder to the bucket.

1. Extend or retract the bucket cylinder slightly to align the link eye with the second set of ears on the bucket.

2. Insert the Link Pin (Bottom Pin):

   • Align the link with the bucket ears.

   • If the bucket has multiple hole positions (for different digging forces), ensure you select the correct hole for the required application (standard power vs. high power/speed).

   • Insert the pin.

   • Install retainers. Hitachi often uses a bolt and keeper or a circlip for this pin.

   • Note: On some large Hitachi excavators, the link pin is installed first into the link, and then the link is pinned to the bucket.

Step 4: Tighten & Torque

1. Torque Retainer Bolts:

   • Hitachi uses specific high-strength bolts for the pin retainers. If these bolts are stretched or damaged, replace them.

   • Apply Loctite (usually medium strength 242) if specified in the service manual.

   • Torque to the specific Nm (lb-ft) rating for your machine size (e.g., ZX350 and above often require 400–700 Nm).

2. Check Thrust Clearance:

   • After pinning, ensure the bucket has slight lateral movement (0.5mm to 2mm gap) between the bucket ears and the stick/link. If it is bound tight, the bushings are misaligned or dirt is trapped.

Step 5: Grease & Cycle

1. Connect the grease gun to the zerks on the arm and the link.

2. Pump grease until old grease (if any) purges out from the pin seals.

3. Start the engine.

   • Cycle the bucket curl and dump functions slowly 5–10 times at low RPM.

   • This seats the pins and distributes the grease.

4. Re-grease after cycling to fill the void created by the pin movement.

Important Considerations for Hitachi Specifics

• Pin Retention: Unlike Cat or Deere which often use through-bolts, Hitachi medium/large excavators frequently use "cap and bolt" retention. The pin has a flat machined face that a metal cap bolts over. Do not operate the machine if these bolts are loose; the pin will walk out, causing catastrophic damage to the stick ears.

• Bushing Fit: If you replaced bushings in the stick or link, they often require line-boring after welding to ensure the bores are perfectly coaxial (aligned with each other). If the bores are off by even 1mm, installing the pin will be impossible without extreme force, which will lead to premature failure.

• Lifting Capacity: A Hitachi ZX350 bucket weighs over 1,500 kg (3,300 lbs). Always verify the lifting capacity of your crane or supporting machine before lifting.