350-3843 CAT 773D / 773E / 773G Front Suspension Cylinder Aftermarket Replacement

Product Overview

SEIGO’s aftermarket front suspension cylinder, part number 350-3843, is a direct drop-in replacement for the Caterpillar 773D, 773E and 773G off-highway rigid-frame mining dump trucks. Unlike the hydraulic cylinders that move an implement, a suspension cylinder is a gas-over-oil strut: it carries the static and dynamic load of the truck corner, damps road-induced shock, and maintains ride height. On a rigid-frame haul truck loaded to 50-plus tonnes of payload running a rough haul road shift after shift, the front suspension struts are among the hardest-worked structural components on the machine.

Caterpillar catalogues this part within the front suspension group 664-1890, and it belongs to a supersession chain that includes the earlier references 264-5784, 296-0736 and 298-3926. All of these numbers refer to the same front suspension cylinder position across successive revisions of the 773 platform, which is why a truck built in different years may show a different number in its parts book while requiring the same physical strut. Part 350-3843 is the front strut — it should not be confused with the rear suspension cylinder 350-3849, which belongs to a different group (664-1882) and is not interchangeable.

The failure pattern on a suspension strut is distinct from an implement cylinder. Rather than seal extrusion from work pressure, the dominant issues are nitrogen charge loss through the rod seal, rod chrome pitting from stone impact on the haul road, and internal bleed-down that lets the truck corner sag over time. SEIGO manufactures the 350-3843 to address exactly these: a 42CrMo4 induction-hardened, hard-chrome-plated rod finished for stone-impact resistance, a high-integrity rod seal and gas-charge sealing package rated to the strut’s 247 bar working pressure, and a barrel machined to hold charge over long service intervals. Every unit is pressure and charge tested before shipment from our Guangdong factory and is backed by a 12-month or 5,000 operating-hour warranty. Standard lead time is approximately 30 days ex-works, with expedited production available for mine-site downtime.

Product Specifications

* OEM part numbers, brand names and model designations are used for identification and cross-reference purposes only. SEIGO Machinery is an independent aftermarket manufacturer and is not affiliated with Caterpillar Inc.

350-3843 Part Number Cross-Reference & Supersession Chain

The front suspension cylinder for the Cat 773 platform has carried several part numbers across production years. All of the numbers below refer to the same front suspension position within group 664-1890 and are cross-referenced in Caterpillar suspension group documentation.

If the number in your parts book is 264-5784, 296-0736 or 298-3926, 350-3843 is the current-specification replacement for the same front strut position. Confirm your machine serial number before ordering, as suspension specification can vary with build year and payload configuration.

Cat 773 Suspension Cylinder Reference — Front vs Rear

A rigid-frame haul truck uses different suspension struts front and rear, and they are not interchangeable. Ordering the wrong position is the most common error on suspension strut purchases.

350-3843 is the front strut. The rear strut 350-3849 belongs to a different suspension group and has different dimensions and charge specification. If you are replacing struts on both axles, order both positions; if replacing one, confirm which corner has failed. SEIGO supplies both front and rear suspension cylinders for the 773 platform — send us your machine serial number to confirm the correct part for each position.

Why This Cylinder, Specifically

• Correct position and supersession, verified. Front and rear struts differ, and the front strut itself carries four part numbers across production years (264-5784, 296-0736, 298-3926, 350-3843). We confirm the position and the current specification against your serial number before quoting — the wrong strut on a haul truck corner causes ride-height and handling problems from the first shift.
• Built for charge retention. The defining failure mode of a suspension strut is nitrogen charge loss, not work-pressure seal blow-by. We fit a high-integrity rod seal and gas-charge sealing package rated to the 247 bar working pressure, and machine the barrel to hold charge across long service intervals.
• Stone-impact rod finish. Front struts sit low and forward, directly in the stone-throw zone of the haul road. Rod chrome pitting from stone impact is a leading cause of premature seal failure, so the rod is finished specifically for impact and abrasion resistance.
• Replace fronts as a pair. Both front struts on a truck accumulate the same road hours. If one has lost charge or is leaking, the other is usually close behind — replacing the pair in one shutdown avoids a second unplanned stoppage and keeps ride height balanced across the front axle. We supply matched pairs on a single order.
• Full traceability and testing. ISO 9001:2015 manufacturing, pressure and charge tested before shipment, shipped in an ISPM-15 fumigated export crate with material certificate and test record.

FAQ

Q1: What is the difference between 350-3843 and the earlier numbers 264-5784, 296-0736 and 298-3926?

A: They are successive revisions of the same front suspension cylinder for the Cat 773 platform. 350-3843 is the current reference; 264-5784, 296-0736 and 298-3926 are earlier numbers it supersedes. Whichever number appears in your parts book, 350-3843 is the current-specification replacement for that front strut position. All belong to the front suspension group 664-1890.

Q2: Is 350-3843 the front or the rear suspension cylinder?

A: 350-3843 is the front suspension cylinder, part of group 664-1890. The rear suspension cylinder for the same trucks is 350-3849, which belongs to a different group (664-1882) and is not interchangeable. Confirm the position before ordering — front and rear struts have different dimensions and gas-charge specifications.

Q3: Which trucks does 350-3843 fit?

A: The core applications are the Caterpillar 773D, 773E and 773G rigid-frame off-highway trucks. The number also appears in cross-reference alongside other 770-series haul trucks (770, 772, 775 variants) depending on build year and suspension configuration. Because suspension specification changes across the 770/772/775 range, send us your full machine serial number and we will confirm fitment before you order.

Q4: Why do front suspension cylinders fail, and what are the warning signs?

A: The most common failure is gradual nitrogen charge loss, which shows as one front corner sitting lower than the other, a harsher ride, or the truck bottoming out over bumps it used to absorb. Oil weeping at the rod, and visible pitting or scoring on the exposed rod chrome from haul-road stone impact, are also warning signs. Because the two front struts share the same road hours, a fault on one is a strong indicator to inspect the other.

Q5: Do you supply the rear suspension cylinder and seal kits as well?

A: Yes. SEIGO supplies both the front (350-3843) and rear (350-3849) suspension cylinders for the 773 platform, and also supplies seal kits, rod seals, gas-charge seals and bushings as individual service items for workshops rebuilding struts in-house. Send us your machine serial number and the part or component you need for a quotation.

Q6: What is the lead time and how does the strut ship?

A: Standard production lead time is approximately 30 days ex-works Guangdong, China, with expedited production available for mine-site downtime. Each strut ships in an ISPM-15 fumigated wooden export crate, FOB Shenzhen, CIF or DDP. At approximately 375 kg per unit, sea freight is standard for planned replacements; air freight is available for urgent situations.

SEIGO Machinery is an independent aftermarket manufacturer. All OEM part numbers, brand names and machine model designations are used for identification and cross-reference purposes only. These aftermarket components are not manufactured by, endorsed by, or affiliated with Caterpillar Inc.