QJ1254.31.021 Hydraulic Steering Cylinder for Tractor | 65mm Bore

QJ1254.31.021 Hydraulic Steering Cylinder for Tractor — 65 mm Bore × 250 mm Stroke QJ1254 Large-Platform OEM Steering Ram

OEM Part Number	QJ1254.31.021
Bore Diameter	65 mm
Rod Diameter	36 mm
Stroke	250 mm
Mounting Distance (C-C)	650 mm
Cylinder Type	Double-Acting, Single Body
Seal Material	PU Primary + NBR Backup

Request Pricing — QJ1254 Series

65 mm bore · 250 mm stroke · 650 mm C-C · FOB Ningbo

Engineering Overview: QJ1254.31.021 Large-Bore 65 mm Tractor Steering Cylinder for the High-Horsepower QJ1254 Platform Front Axle

の QJ1254.31.021 Hydraulic Steering Cylinder for Tractor is the largest-bore QJ-series cylinder in this product range and is designed for the QJ1254 platform—a high-horsepower tractor class in the 100–130 hp segment where front axle static loads, four-wheel-drive torque reactions, and implement draft forces combine to place the steering system under the highest sustained hydraulic demand encountered in this series. The QJ1254 platform designation follows the same numeric convention as QJ554 and QJ904: the number reflects an approximate horsepower-class identifier within the Qujiang tractor family. The “021” drawing number increments sequentially from the QJ904’s “019” code, confirming that the QJ1254 steering cylinder was designed as a deliberate engineering step-up from the QJ904 specification rather than a separate product development.

The 65 mm bore is the largest in this twelve-product series and produces 39.8 kN extension force at 12 MPa—6.4% higher than the QJ904’s 63 mm bore output. This incremental bore increase from 63 mm to 65 mm is a calibrated design decision: the QJ1254 front axle carries a higher static load than the QJ904, but the hydraulic circuit pressure remains at 12–14 MPa (unchanged from lighter machines), so the only path to greater steering force is a larger bore. The 36 mm rod—incremented by 1 mm from the QJ904’s 35 mm rod—maintains a closely matched bore-to-rod area ratio while providing a slightly higher buckling load: at 250 mm stroke under fixed-pinned conditions, the 36 mm rod yields an Euler buckling load of approximately 164 kN, giving a 4.1× safety factor over the rated extension force. The 650 mm C-C is the second-longest in this series, 11 mm wider than the QJ904’s 639 mm, reflecting the QJ1254’s wider front axle beam width.

This cylinder is specified for tractors engaged in heavy primary tillage, deep-ripping, and large-implement field preparation in markets including Australia, Canada, and Brazil, where high-horsepower tractors operate at sustained hydraulic demand for extended field hours with minimal downtime tolerance. The 650 mm C-C and 65 mm bore combination is also found on several export-market tractors produced under OEM licensing from Chinese manufacturers targeting these large-acreage farming segments.

Hydraulic Specifications: 65 mm Bore Force Output, Pump Flow Demand, and Seal Configuration for the QJ1254 250 mm Stroke Tractor Steering Cylinder

Bore area is 3,318 mm²; rod area is 1,018 mm² (36 mm rod). At 12 MPa, extension force is 39.8 kN and retract force is 27.6 kN—a retract-to-extend ratio of 69%, matching the QJ904’s ratio closely. Full extension displaces 830 cm³—the highest volume of any cylinder in this series. For a 2.0-second lock-to-lock time, the minimum required pump flow is 24.9 L/min. QJ1254-class tractors are equipped with high-output hydraulic systems typically rated at 30–45 L/min, so the pump capacity requirement is met under normal operating conditions; however, at low idle or cold-start when hydraulic fluid viscosity is elevated, the effective pump output may temporarily fall below 25 L/min and produce a briefly sluggish steering response that resolves within minutes of warm-up. This is normal behaviour for this cylinder class and should not be interpreted as a seal or valve fault.

Barrel tube is 20# seamless precision steel, honed to Ra ≤ 0.4 µm across 250 mm stroke. Rod is 40Cr alloy steel (AISI 5140), heat-treated to 28–32 HRC core hardness, hard chrome plated to 25–30 µm, ground to h6 tolerance on the 36 mm diameter. The 36 mm rod chromium surface at full extension—250 mm exposed length—is the largest single exposed chrome zone in this series. The 25–30 µm plating thickness is the standard specification, with an optional 30–35 µm heavy-duty coating available for customers in coastal or chemical-spray agricultural environments where the standard thickness does not meet the target corrosion resistance period. Seal kit: PU piston U-ring, NBR O-ring secondary, PU rod U-seal, and reinforced-fabric PU wiper seal for the 36 mm rod OD. Given the high bore area and correspondingly high piston seal contact perimeter, the PU compound specification requires a Shore A hardness of 92±3 to maintain adequate seal preload at the 65 mm bore without producing excessive friction at the gland seal interface.

OEM Cross-Reference: Distinguishing QJ1254.31.021 from QJ904.31.019 — Bore, Rod, C-C, and Clevis Pin Differences Between Adjacent QJ-Series Steering Cylinders

The QJ1254.31.021 and QJ904.31.019 (Product 10) are the most visually similar cylinders in this entire series: both share a 250 mm stroke and are externally close in overall length, but differ in bore (65 mm vs. 63 mm), C-C (650 mm vs. 639 mm), rod diameter (36 mm vs. 35 mm), and clevis pin (34 mm H7 vs. 32 mm H7). The 34 mm clevis pin on the QJ1254.31.021 is the largest in this twelve-product series. A 34 mm pin bored into a 32 mm H7 clevis produces a 1 mm interference that prevents assembly; a 32 mm pin in a 34 mm H7 clevis produces 1 mm radial play that generates destructive impact fatigue at the clevis root within a few hundred operating hours. Five-parameter verification is mandatory: 65 mm bore, 36 mm rod, 250 mm stroke, 650 mm C-C, 34 mm clevis pin. Barrel OD visual inspection can separate the two models—the 65 mm bore barrel is measurably wider than the 63 mm bore barrel—but dimensional certification from the supplier is the only reliable verification method for bulk procurement.

Installation, Cold-Start Steering Behaviour, and Maintenance Programme for the QJ1254.31.021 Large-Bore Tractor Hydraulic Steering Cylinder

Torque 34 mm clevis pin retention fasteners to 85–95 N·m. Port connections are M22×1.5; torque to 90–105 N·m with new bonded seals. Fill the hydraulic reservoir to maximum before starting—the QJ1254-class circuit volume can absorb 2.0–2.5 litres during initial cylinder fill, requiring a post-bleed top-up. Bleed with ten full lock-to-lock cycles at low idle, then two additional cycles at normal operating RPM to confirm firm, consistent steering feel at higher flow rates. Cold-start sluggish steering (as described in Section 2) is an expected normal behaviour during the first 5–10 minutes of operation at ambient temperatures below 10°C; operators unfamiliar with large-bore cylinder behaviour sometimes interpret this as a hydraulic fault. Including a note in the operator manual supplement—available as part of the OEM white-label documentation package—prevents unnecessary warranty return claims driven by this normal characteristic. Seal inspection at 500-hour intervals; full seal kit replacement at 2,000 hours standard, or 1,500 hours in sustained heavy primary-tillage applications.

Factory Testing, High-Force Pressure Rig Specification, and B2B Procurement for the QJ1254.31.021 65 mm Bore Tractor Steering Cylinder

Proof test at 21 MPa static produces approximately 69.7 kN total force on the test rig fixture—the highest in this series. The test rig is rated to 30 MPa with a 600 kN reaction frame capacity. Proof test duration: 5 minutes per stroke direction; 20 dynamic cycles at rated pressure. Internal leakage acceptance: ≤4 mL/min at the piston seal. Bore taper measurement at three axial positions is included in each shipment’s dimensional inspection report. Chrome rod samples: 240-hour ASTM B117 per batch. Barrel exterior: two-component epoxy primer with optional 30–35 µm heavy-duty chrome rod coating upgrade. MOQ: 10 units; standard pallet: 20 units. Lead time: 10–15 working days FOB Ningbo. Custom options: 40 mm rod upgrade for maximum buckling margin, modified port orientation, FKM seals, heavy-duty chrome rod plating, electroless nickel barrel coating. OEM white-label documentation in English, Spanish, Portuguese, or Korean, including operator manual supplement addressing cold-start steering behaviour.