YD40-270 Header Cylinder | 896mm Mounting Length, 45mm Bore, 270mm Stroke

Model: YD40-270

YD40-270 Header Cylinder — Long-Stroke Combine Platform

The YD40-270 header cylinder stands apart from other combine header actuators in this lineup by one defining dimension: a 896 mm closed mounting length. This is not a compact positioning cylinder — it is a structural hydraulic actuator designed for combine platforms with extended header geometry, where the lift linkage requires a long cylinder to span the distance between the chassis mounting point and the header pivot arm.

Key Specifications

Bore Diameter45 mm
Rod Diameter40 mm
Stroke270 mm
Mounting Length896 mm

YD40-270 Header Cylinder 896mm Mounting Length: Why This Dimension Defines the Application

A 896 mm pin-centre closed length is the most distinctive feature of the YD40-270, and it immediately constrains the machine platforms this cylinder is compatible with. Most combine header lift cylinders in the mid-range agricultural market have closed lengths in the 380–520 mm range. The YD40-270’s 896 mm mounting length places it in a category designed for larger or differently configured machines — typically combines with elevated header pivot points, extended lift arm geometry, or designs where the cylinder mounts low on the chassis and extends upward to a high-mounted header pivot.

This long mounting configuration has real mechanical implications. A cylinder with 896 mm closed length and only 270 mm stroke is operating with a high body-to-stroke ratio — the cylinder body is long relative to its active travel. This design keeps the cylinder operating within a moderate extension ratio across its stroke range, which is beneficial for rod stability: at any point in the stroke, the exposed (unsupported) rod length remains within safe column buckling limits for the 40 mm rod diameter specified.

The 40/45 rod-to-bore ratio (89%) on the YD40-270 is among the highest in this product range. A near-full-bore rod generates nearly symmetric push and pull forces, which matters in long-body cylinder applications where both extension and retraction loads can be substantial due to the weight distribution of the header and the changing mechanical advantage of the lift linkage across the stroke.

At 150 bar system pressure and 45 mm bore, the YD40-270 delivers approximately 23.8 kN push force — a moderate figure that reflects the fact that this cylinder is sized for a specific machine geometry, not for maximum force output. The lift linkage mechanical advantage does the amplifying work; the cylinder delivers the input force at the right travel distance.

Long Stroke Combine Header Cylinder Replacement: Verification Steps Before Ordering

Because the YD40-270 has a closed length approximately 85% greater than a standard compact header cylinder, sourcing errors — ordering the wrong variant — are more consequential. A mismatched closed length on a long-body cylinder cannot be corrected with spacer brackets without fundamentally altering the lift linkage geometry. We strongly recommend a three-point verification process before placing orders for this model:

• Step 1 — Measure closed length on the existing cylinder: With the cylinder fully retracted and removed from the machine, measure pin-centre to pin-centre. This should read 896 mm ± 2 mm for the YD40-270. If the measurement differs by more than 5 mm, you are looking at a different variant.
• Step 2 — Confirm bore and rod diameters: Measure the rod diameter (should be 40 mm) and, if possible, estimate bore diameter from the cylinder barrel outer diameter or from the machine’s parts manual. Bore measurement of the existing part is not always practical in the field, but rod diameter measurement requires only a calliper.
• Step 3 — Photograph port location and end-cap configuration: The port thread location and clevis orientation determine hose routing compatibility. Send us these photos along with your bore-rod-stroke measurements and we will confirm part compatibility before shipment.

For distributors who supply multiple combine models, maintaining a cross-reference database that maps machine serial number ranges to cylinder part numbers eliminates this verification step for repeat orders. We can assist in building this reference for the combine models your customer base operates.

Structural and Sealing Engineering for a High Aspect Ratio Cylinder Body

Manufacturing a cylinder with a 896 mm body and 270 mm stroke requires attention to straightness and concentricity tolerances that shorter cylinders can achieve more easily. If the barrel tube has even a small bow — within tolerance for a 500 mm cylinder — that bow becomes amplified in relative terms for a 900 mm tube, and the resulting bore-to-rod misalignment accelerates piston and rod seal wear from the first hours of operation.

For the YD40-270, barrel tube straightness is held to ≤ 0.3 mm over the full tube length before honing. After honing, cylindricity is verified to H8 tolerance across the full bore length, not just at the seal contact zones. This ensures that the piston assembly maintains designed running clearance throughout the stroke without localised tight spots that would appear as pressure spikes in slow, load-controlled header lowering.

The 40 mm rod is produced from 45# or 40Cr steel (depending on working pressure specification), drawn and ground to h6 tolerance with a chrome surface of ≥ 25 µm minimum thickness. At this rod diameter and with the extended body length, the rod operates across a maximum extension of 270 mm from the gland — a safe ratio for the 40 mm rod given the 45 mm bore providing adequate guide ring bearing area in the gland assembly.

Welded end closures (or machined thread-in closures depending on pressure rating) are subjected to full-penetration weld inspection and hydrostatic proof testing at 1.5× rated pressure. Because of the long body, handling during pressure testing and shipping requires specific orientation and support to prevent deformation — we ship the YD40-270 in custom wooden crates with full-length barrel support to ensure dimensional integrity on delivery.

Logistics and Supply Considerations: Long-Body Cylinder Shipping and Stocking

At approximately 900 mm in closed length, the YD40-270 falls into the dimensional category that affects both packaging and freight cost calculations. Key logistics points for importers and distributors:

• Carton dimensions: Each cylinder ships in a 1,000 × 160 × 160 mm carton. Case quantities of 4 or 6 pcs can be palletised for sea freight efficiency. Weight per piece approximately 4.5–5.5 kg depending on end fitting configuration.
• Air freight feasibility: At this length and weight, air freight is economical for 1–4 pc emergency orders. Cost per piece is higher than small-bore cylinders but remains viable compared to machine downtime cost during harvest season.
• Warehouse shelving: Long cylinders require horizontal shelving at 1,000 mm clear depth. Vertical storage is not recommended for cylinder assemblies of this length — the rod seal can be stressed by the hanging weight of the extended rod.
• Minimum stock recommendation: Distributors serving markets with 3–5 machines using this model should maintain a minimum of 4–6 pcs per season. Given the long mounting length, this is a low-substitutability part — there is no short-notice workaround if the replacement is not in stock.

Complete Technical Specifications