Idler Wheel (Guide Wheel) for Hitachi EX1200-6 Excavator | YA00035320
Keywords：
Category：
- Detail
-
- Commodity name: Idler Wheel (Guide Wheel) for Hitachi EX1200-6 Excavator | YA00035320
Hitachi EX1200-6 Excavator YA00035320
Idler Wheel (Guide Wheel) for Hitachi EX1200-6 Excavator | YA00035320
Product Overview
The idler wheel (also known as guide wheel or front idler) is a critical undercarriage component of your Hitachi EX1200-6 mining excavator. Positioned at the front of the track frame, this non-driven wheel serves as the forward pivot point for the track chain, providing guidance, maintaining proper alignment, and working in conjunction with the hydraulic track adjuster to maintain optimal track tension. It is designed to withstand the immense shock loads and abrasive conditions of mining environments.
The Hitachi EX1200-6 is a 112–114 ton class mining excavator powered by a Cummins QSK23 engine producing 567 kW (760 HP). This genuine Hitachi idler wheel assembly (Part No. YA00035320) is engineered to exacting OEM specifications for perfect fit, reliable performance, and maximum service life in demanding mining applications.
This is a genuine Hitachi original equipment part.
Note:YA00035320 is the complete idler assembly. The part number YA00035319 refers to the same assembly, and YA00035320PS is an alternative reference. This idler assembly is also compatible with EX1200-7 models .
Technical Specifications
Parameter
Specification
Part Number
YA00035320
Alternate/Cross Numbers
YA00035319, YA00035320PS, 4696615
Manufacturer
Hitachi Construction Machinery
Component Type
Idler wheel / Guide wheel / Front idler assembly
Application
Track chain guidance and tensioning
Machine Model
EX1200-6 Mining Excavator
Also Compatible With
EX1200-7
Operating Weight
112 t (112,000 kg)
Engine Power
567 kW (760 HP)
Engine Model
Cummins QSK23
Material
Forged high-tensile alloy steel (Cr-Mn-B or Ni-Cr-Mo alloy)
Surface Hardness
58–62 HRC (hardened wear layer 8–12 mm depth)
Flange Design
Robust dual-flange for lateral guidance
Bearing Type
Double-row spherical roller bearing / Tapered roller bearing
Seal Type
Multi-barrier system (labyrinth + floating face seal + lip seal)
Lubrication
EP lithium-complex grease (grease nipple equipped)
Mounting Type
Adjustable carriage on track frame, interfaces with hydraulic tensioner
Please verify exact specifications with your machine's technical manual or existing component.
EX1200-6 Undercarriage Overview
The Hitachi EX1200-6 features a reinforced undercarriage system designed for extreme mining conditions . According to Hitachi documentation, undercarriage components are manufactured using high-quality materials and tested under the toughest conditions .
Component
Function
Idler Wheel (YA00035320)
Forward track pivot, guidance, tensioning interface
Track Chain Assembly
Continuous chain with pins and bushings
Track Shoes
Individual pads for ground contact
Drive Sprocket
Engages bushings to propel machine
Track Rollers (Lower)
Support machine weight on track frame
Carrier Rollers (Upper)
Support upper track run
Track Adjuster Cylinder
Hydraulic cylinder for tensioning (interfaces with idler)
Key Undercarriage Features
- Hitachi Genuine Undercarriage designed specifically for EX1200-6
- High-quality materials guarantee reliable performance
- Tested under toughest conditions for mining applications
Idler Wheel Components
The idler wheel assembly (YA00035320) integrates several precision-engineered components :
Component
Description
Idler Wheel (Rim)
Forged from high-tensile abrasion-resistant alloy steel; features robust dual-flange design for lateral guidance; running surface deep induction-hardened (58-62 HRC, 8-12mm depth)
Idler Shaft (Spindle)
High-yield-strength alloy steel (34CrNiMo6/4340), quenched and tempered; precision-ground journals for seal performance
Bearings
Double-row spherical roller bearings or tapered roller bearings; high radial load capacity with self-alignment capability
Sealing System
Multi-stage: external labyrinth seal (excludes debris) + floating face seal (primary seal against fine abrasives) + secondary lip seal (grease retention)
Hub & Bracket
Heavy-duty forged/fabricated steel; interfaces with track frame sliding tensioning mechanism
Tensioning Interface
Machined socket or forged yoke connecting directly to hydraulic track tensioning cylinder
Function & Operation
Function
Description
Track Chain Guidance
Serves as forward pivot and guide for track chain, ensuring precise linear travel and preventing mis-tracking
Dynamic Track Tensioning
Mounted on adjustable carriage, actuated by hydraulic tensioner for precise track sag control
Shock Load Absorption
Absorbs and dissipates initial impact loads from terrain irregularities and rock impacts
Track Link Articulation
Provides smooth, hardened surface over which track chain bushings pivot
Operating Principle
- Idler wheel rotates as track chain moves around the undercarriage
- Dual flanges guide track chain laterally, preventing derailment during turning and side-slope operations
- Hydraulic track adjuster pushes idler assembly forward to maintain proper track tension
- Internal bearings allow smooth rotation while supporting machine weight
- Multi-barrier sealing system protects bearings from abrasive mining contaminants
Integration with EX1200 Undercarriage System
The front idler wheel assembly works in concert with the final drive sprocket at the rear, guides the track chain over the upper carrier rollers and lower track rollers, and its adjustable position directly governs track sag and ground contact length .
Compatible Hitachi Models
Series
Models
Primary
Hitachi EX1200-6 Mining Excavator
Also Compatible
EX1200-7
Important:Please verify your machine's serial number with our parts department to ensure correct compatibility. The EX1200-6 was manufactured from 2007 to 2012, and serial number verification is important for ensuring correct fitment.
Cross Reference Information:The idler assembly YA00035320 is also known by the following alternate part numbers :
- YA00035319
- YA00035320PS
- 4696615
Genuine Hitachi Quality
Component
Feature
Benefit
Idler Body
Hot-forged from high-alloy steel (Cr-Mn-B / Ni-Cr-Mo)
Exceptional impact toughness and fatigue resistance
Wear Surface
Submerged arc hard-facing / deep induction hardening (58-62 HRC, 8-12mm depth)
Extended wear life in abrasive mining environments
Flanges
Precision-machined dual-flange design
Unwavering lateral guidance, prevents de-tracking
Sealing System
Multi-barrier: labyrinth + floating face seal + lip seal
Superior contamination protection, extended bearing life
Bearings
Double-row spherical / tapered roller
Ultra-high radial load capacity, self-alignment capability
Shaft
High-yield-strength alloy steel, precision-ground journals
Maximum bending and shear strength, perfect seal performance
Key Features
- Forged construction provides superior grain flow and structural integrity compared to cast components
- Precision-machined guide channel matches track chain guide lugs for positive centering
- Multi-stage sealing system critical for extended service life in high-cost-per-hour mining operations
- Heavy-duty rock guard protects vulnerable parts from debris
- Designed and engineered specifically for EX1200-6
- Direct replacement for original equipment
Common Failure Signs
Symptom
Likely Cause
Rapid flange wear
Chronic operation on abrasive side slopes, improper track tension, undercarriage misalignment
Track derailment
Worn flanges beyond service limit, improper tension
Unusual noise from front of track
Bearing wear, seal failure
Idler does not rotate freely
Bearing failure, seal damage, contamination ingress
Grease leakage from idler
Seal failure, floating face seal damage
Visible flange wear or "hooking"
Normal wear beyond service limit
Idler rim cracking or spalling
Thermal stress from hard-facing, extreme impact events, material fatigue
Bearing seizure
Seal failure leading to contamination ingress, lubricant degradation
Shaft failure
Extreme overload scenario (massive side impact) or progressive fatigue crack
Genuine Part Assurance
Assurance
Detail
Authenticity
100% genuine Hitachi part
Condition
New
Warranty
Full Hitachi manufacturer's warranty
Packaging
Original Hitachi heavy-equipment industrial packaging
Origin
Japan
Note:Hitachi Genuine Parts are manufactured using high-quality materials and tested under the toughest conditions to guarantee reliable performance .
Installation Guidelines
Critical Requirements
- Verify part number matches your machine's requirements
- Prepare adequate heavy lifting equipment - Idler assembly is heavy
- Support machine securely with track blocked
- Relieve track tension before removal using track adjuster grease valve
- Maintain cleanliness - Contamination causes premature seal and bearing failure
- Reference EX1200-6 Workshop Manual for complete procedures
Installation Steps
- Position machine on level ground, block tracks securely
- Relieve track tension using track adjuster grease valve
- Remove track chain or create slack for idler access
- Clean idler area thoroughly
- Remove mounting bolts or retainers securing idler
- Remove old idler assembly from track frame
- Clean idler mounting surface and slide rails
- Inspect adjuster cylinder rod for damage
- Inspect idler mounting slide rails for wear
- Install new genuine Hitachi idler wheel (YA00035320)
- Apply grease to slide surfaces if specified
- Install retaining hardware and torque to Hitachi specifications
- Apply track tension to specification using track adjuster
- Reinstall track chain if removed
- Test track operation in forward and reverse at low speed
- Re-check track tension after initial operation
Post-Installation
- Verify idler rotates freely
- Check for proper track alignment
- Inspect for unusual noise during track operation
- Re-check track tension after initial operation
- Re-torque mounting hardware after initial operation (if specified)
Critical Wear Limits
Hitachi provides strict maximum wear limits for the idler wheel's flange height and rim diameter. Operating beyond these limits (e.g., >20mm diameter reduction) drastically increases the risk of de-tracking and causes accelerated wear to the track chain, bushings, and rollers .
IMPORTANT:Installation must only be performed by qualified mining equipment technicians following procedures in the EX1200-6 Workshop Manual, specifically the Undercarriage section.
Maintenance Recommendations
Interval
Maintenance Task
Daily
Visual inspection for damage, unusual noise, track alignment
Weekly
Check for proper rotation, inspect seals for leakage
Monthly
Grease idler fittings (if applicable); check flange wear
Every 500 hours
Check for wear, measure idler diameter; inspect seal integrity
Every 1000 hours
Check idler alignment with track chain
Every 2000 hours
Inspect bearings and seals
Every 5000 hours
Perform detailed undercarriage inspection
As Needed
Replace when worn or damaged
Track Tension Management
Adherence to the manufacturer's specified track sag (typically 40-60 mm for a machine of this size) is non-negotiable for maximizing component life and minimizing power loss :
- Over tightening increases rolling resistance and load on idler bearings
- Under tightening causes track whipping and uneven wear
- Refer to EX1200-6 Operator's Manual for specific track sag specifications
Critical Notes
- Always use genuine Hitachi replacement parts
- Regular inspection for seal integrity (looking for grease leakage or contamination ingress) is essential
- Worn idler accelerates track chain and adjuster wear
- Replace idler in pairs for even undercarriage wear (both sides)
- Proper track tension is critical for idler and track chain life
- Proactive seal and lubrication maintenance prevents catastrophic bearing failure
Ordering Information
Part Number: YA00035320
Alternate Numbers:YA00035319, YA00035320PS, 4696615
Product Name:Idler Wheel / Guide Wheel / Front Idler Assembly (Genuine Hitachi)
Application:Hitachi EX1200-6 Mining Excavator
Also Fits:EX1200-7
Condition:New Genuine OEM Part
Recommended Related Parts
Component
Part Number
Notes
Track Adjuster Cylinder
9271451
Interfaces with idler assembly
Track Chain Assembly
YA00057804
Inspect during idler replacement
Drive Sprocket
4661591
Inspect for wear
Track Roller (Lower)
Contact parts department
8-10 per side
Carrier Roller (Upper)
YA60086384
3 per side
Adjuster Seal Kit
Contact parts department
If adjuster service needed
Quantity per Machine
The Hitachi EX1200-6 is equipped with 1 idler wheel per side(total of 2 per machine).
Service Manual Reference
The EX1200-6 idler wheel and undercarriage system are documented in the following factory service publications:
Document
Reference
Content
Workshop Manual
EX1200-6 Workshop Manual
SECTION 3 UNDERCARRIAGE - Front Idler
Technical Manual (Operational Principle)
EX1200-6 Technical Manual
Component operation theory
Technical Manual (Troubleshooting)
EX1200-6 Technical Manual
Diagnostic procedures
For complete service information including torque specifications and wear limits, refer to the official Hitachi EX1200-6 Workshop Manual.
Product Source Information
The idler wheel assembly YA00035320 is available through authorized Hitachi parts distribution channels . For EX1200-6 undercarriage components, it is recommended to contact parts specialists with your machine serial number for accurate compatibility verification. The EX1200-6 was manufactured from 2007 to 2012, and serial number verification is important for ensuring correct fitment.
Hitachi EX1200-6 is a registered trademark of Hitachi Construction Machinery. All genuine parts are sourced through authorized distribution channels. Specifications and design subject to change without notice.
Factory
Factory 05
Factory 04
Factory 03
Factory 02
Inquiry
