Caterpillar 320B Main Control Valve Assembly (OEM 126-2068 / 121-1490)

The hydraulic command network on the legendary 20-ton Caterpillar 320B excavator directs dual-pump oil flow to execute simultaneous boom elevation, arm crowding, and swing cycles. Tatan Machinery supplies 100% Brand New multi-spool hydraulic main control valve assemblies (OEM reference: 126-2068 / 121-1490, interchangeable with 145-6379 / 116-6731). Featuring hardened alloy steel spools micro-lapped to factory tolerances, each complete valve block eliminates internal pressure bypass, resolves cylinder drift, and restores factory digging speed to aged 320B fleets. Backed by our 12-Month Comprehensive Replacement Warranty.

Verified Wholesaler & Direct Stockholding Proof

Tatan Machinery is a verified stocking exporter and wholesaler of heavy excavator hydraulic assemblies. We maintain physical inventory for independent repair shops, commercial fleets, and overseas parts retailers. All hydraulic pumps, main valves, and travel drives supplied on our site are 100% Brand New (diesel engines are remanufactured to OEM tolerances).

Field Diagnostics: Why Rebuilding Worn CAT 320B Control Valves Fails

The CAT 320B is one of the most reliable 20-ton earthmovers ever produced, but after 20,000+ service hours, worn internal valve tolerances cause severe performance loss that simple seal kits cannot fix:

• Internal Valve Bore Ovality & Severe Oil Slippage: Millions of high-pressure flow cycles wash out the cast iron internal bores. Once clearance between the spool and the casting exceeds 0.02mm, hydraulic fluid slips continuously into the tank gallery. The machine loses digging speed as soon as oil warms up past 50°C.
• Boom Flow-Merging Spool Jamming: Dual-pump flow integration on the 320B relies on precise spool metering lands. Silt and metal debris gall the spool edges, preventing pump 1 and pump 2 from combining. The boom raises at half-speed when crowding the stick.
• Eroded Holding Valve Seats & Uncontrolled Cylinder Drift: Anti-drift poppets develop microscopic grooves on their sealing tapers. A suspended bucket of gravel creeps down rapidly with joysticks in neutral, creating safety hazards on commercial jobsites.
• Fatigued Inter-Section Mating Lands: Years of hydraulic shock fatigue the internal partition walls between the front and rear blocks. High-pressure oil bleeds into the swing circuit, causing uncommanded cab rotation when tracking.

Factory Dyno Testing & 12-Month Component Warranty

To guarantee factory breakout force and cycle speed overseas, every 126-2068 control valve is bench-tested on our automated digital hydraulic test stand before export approval:

1. Main & Port Relief Setting Lock: Main relief cartridges set and locked to Cat 320B factory specifications (34.3 MPa working relief) on our high-pressure test stand.
2. Spool Neutral Holding & Bypass Leakage Test: Individual circuit testing under full working pressure to verify zero cylinder creeping and tight check-valve seat sealing.
3. Flow-Merging Spool Actuation Timing: Dynamic pilot actuation testing to verify seamless hydraulic oil merging for fast boom-up and stick-in cycle times.
4. Straight-Travel Logic Verification: Testing the dedicated straight-travel spool under simultaneous tracking and boom actuation to ensure straight-line tracking without steering veer.

Export Heavy-Duty Packaging Protocol

A heavy 160 kg valve block requires clinical protection against contamination and transit shock:

• Solid Steel Port Blanking: All SAE high-pressure split-flange ports and pilot connections sealed with O-ring steel blanking plates.
• VCI Vapor-Phase Anti-Corrosion Wrap: The bare valve block is coated with rust-inhibiting hydraulic film and hermetically vacuum-sealed in VCI plastic foil.
• Custom Internal Structural Timber Bolting: The valve block is bolted down to heavy timber skids to prevent tipping.
• ISPM 15 Fumigation-Free Solid Plywood Box: Fully enclosed export crate banded with multiple high-tensile galvanized steel straps.

Supported Global Logistics & Customs Documentation

Prompt logistics dispatch adapted for urgent machine-down emergencies and trade stock:

• Air Express (3–7 Days Door-to-Door): Handled via DHL Express, FedEx, or air cargo for rapid jobsite recovery.
• Sea Freight Consolidation: Economical LCL shipping for distributors stocking multiple units.
• Tariff-Ready Paperwork: Commercial invoice detailing official HS Code (8481.20 – Valves for Oleohydraulic Transmission), packing lists, and Certificate of Origin (COO) upon request.

Daily overseas air express dispatches and consolidated container freight

Critical Installation Guidelines (CAT 320B Hydraulic Technician Checklist)

To prevent instant spool contamination and maintain your 12-month warranty, technicians MUST adhere to these field rules:

1. MANDATORY: Drain & Chemical Flush Hydraulic Oil Tank: If the previous valve block was replaced due to pump disintegration, metallic particles coat the tank floor. You MUST drain all old fluid, clean the reservoir floor, and install brand-new suction and return filter elements!
2. Reverse-Flush Steel Delivery Hardlines: High-pressure hardlines between the SBS80 main pump and the 126-2068 valve block must be chemically flushed. A single trapped metal flake will instantly score a brand-new spool bore!
3. Pre-Fill Pilot Filter & Purge Air: Fill the pilot circuit filter bowl with clean hydraulic oil. Air trapped in the pilot logic lines will cause jerky joystick response and violent pressure spikes.
4. SAE Split-Flange Torque Pattern: Lubricate all SAE Code 62 O-rings with clean hydraulic oil. Torque 4-bolt flange clamps evenly in a cross-pattern to prevent high-pressure blowout under 350 bar surges.
5. Initial Relief Pressure Verification: Connect a 60 MPa pressure gauge to the main pump delivery test port. Cycle boom and stick slowly at low idle before placing the machine under heavy digging loads.

Procurement Decision FAQ: What Buyers Ask

🔗 Frequently Purchased Together with CAT 320B Main Control Valve:

• DIESEL ENGINE:
  Caterpillar 320B 3066T Diesel Engine Assembly (125-2988)
  Remanufactured
• HYDRAULIC PUMP:
  SBS80 / AP-12 Hydraulic Main Pump Assembly for Caterpillar 320B
  100% Brand New
• SWING MOTOR:
  M2X150 Swing Motor Assembly for Caterpillar 320B
  100% Brand New
• FINAL DRIVE:
  Final Drive Travel Motor Assembly for Caterpillar 320B
  100% Brand New
• BRAND CATALOG:
  View All Caterpillar Excavator & Heavy Equipment Parts Collection

Get Wholesale Factory Quote for CAT 320B Control Valve 126-2068

Looking for direct factory pricing, stock availability, or 12-month warranty terms for Cat 320B control valves? Contact senior specialist Gavin now!

💡 Fast Quote: Send your machine serial number or old valve nameplate photos for an accurate match within 10 minutes!