Balance Beam Repair Kit – Zoomlion Truck Crane Chassis Suspension

Hardened Steel Components

• 2x Main Pivot Pins – Induction-hardened to 58–62 HRC, chrome-plated barrel

• 4x Tapered Roller Bearings – C3 clearance, pre-greased with lithium complex

• 2x Locking Nuts – Self-locking with nylon insert (reusable up to 5 times)

Wear Parts & Seals

• 4x Composite Bushings – PTFE-lined steel backing, self-lubricating

• 2x Wiper Seals – Double-lip nitrile rubber, dust and moisture exclusion

• 2x O-Ring Gaskets – Viton® for high-temperature resistance (up to 200°C)

Installation Hardware

• 8x Grade 12.9 Hex Bolts – Zinc-flake coated

• 8x Hardened Washers – Through-hardened HRC 38–42

• 1x Molybdenum Disulfide Grease Sachet (30g) – for initial assembly only

  
  

Fitment & Compatibility
This kit directly replaces ZOOMLION part numbers ZL-550-320-BB and TC-550-RK2. It is confirmed compatible with:

• ZOOMLION QY25V – all sub-models

• ZOOMLION QY50V – 2018–2023 production

• ZOOMLION ZTC300 – with single-cab configuration

• ZOOMLION ZTC500 – with load-sensing hydraulics

  Why Choose This Kit Over Generic Alternatives

 1. Metallurgical Integrity
All pins and bushings are vacuum-degassed alloy steel (42CrMo4 equivalent), not mild steel. This reduces galling and spalling under cyclic torsion – a common failure point in aftermarket kits.

2. Precision Machining
Each pin is centerless-ground and super-finished to Ra 0.2 µm surface roughness. This minimises friction and extends grease interval by up to 200 operating hours compared to standard finishes.

3. Sealed-for-Life Strategy
The wiper seals and O-rings are chemically resistant to hydraulic oils, diesel, and road salts – critical for rough-terrain crane applications.

Installation Guidelines (Summarised)

1. Clean the balance beam bore and axle housing with solvent – remove all old grease and metal debris.

2. Inspect the beam for cracks or ovality – if out-of-round exceeds 0.03 mm, re-boring is recommended before fitting.

3. Press the bushings using a hydraulic arbor press – never hammer directly.

4. Apply the supplied moly grease to the pin shank and bearing rollers – do not grease the locking threads.

5. Torque the main nut to 450 Nm, then advance 30° – mark the position with a paint pen for visual inspection.

Shipping, Warranty & Support

• Lead time – in-stock, ships within 24 hours (express available)

• Warranty – 12 months against manufacturing defects or 3,000 operating hours – whichever occurs first

• Technical support – reach our crane parts specialists via the [Contact Us] (internal link) page or call the hotline listed there.