{"id":1472,"date":"2026-08-26T05:14:39","date_gmt":"2026-08-26T05:14:39","guid":{"rendered":"https:\/\/ever-powers.com\/?post_type=product&p=1472"},"modified":"2026-08-26T05:15:49","modified_gmt":"2026-08-26T05:15:49","slug":"ym4p-83-01-corn-harvester-chopper-cylinder","status":"publish","type":"product","link":"https:\/\/ever-powers.com\/de_at\/product\/ym4p-83-01-corn-harvester-chopper-cylinder\/","title":{"rendered":"Corn Harvester Chopper Cylinder YM4P.83.01 \u2013 56mm Bore, 130mm Stroke"},"content":{"rendered":"

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YM4P.83.01 \u00b7 Corn Harvester Series<\/p>\n

Corn Harvester Chopper Cylinder<\/h2>\n

High-force, short-stroke actuator for stalk chopper gap adjustment and blade-engagement mechanisms on 4-row corn harvesters.<\/p>\n

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Bore 56 mm<\/span>
\nRod 50 mm<\/span>
\nStroke 130 mm<\/span>
\nC\/C 390 mm<\/span>
\nPart No. YM4P.83.01<\/span><\/div>\n<\/div>\n
\"YM4P.83.01<\/div>\n<\/div>\n

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Full Specification at a Glance<\/p>\n

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Bore Diameter<\/p>\n

56 mm<\/span><\/p>\n

Push force \u2248 39.4 kN @ 160 bar<\/p>\n<\/div>\n

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Rod Diameter<\/p>\n

50 mm<\/span><\/p>\n

Rod\/bore ratio 0.893 \u2014 structural specification<\/p>\n<\/div>\n

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Stroke<\/p>\n

130 mm<\/span><\/p>\n

Covers full chopper gap adjustment range<\/p>\n<\/div>\n

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Mounting Distance<\/p>\n

390 mm<\/span><\/p>\n

C\/C retracted \u2014 OEM bracket-match dimension<\/p>\n<\/div>\n

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Rated Pressure<\/p>\n

160 bar<\/span><\/p>\n

Continuous working pressure<\/p>\n<\/div>\n

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Surge Pressure<\/p>\n

250 bar<\/span><\/p>\n

Blade-strike shock rating \u2014 proof-tested<\/p>\n<\/div>\n

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Rod Chrome<\/p>\n

25\u201330 \u00b5m<\/span><\/p>\n

Hard chrome HV 800+, full rod length<\/p>\n<\/div>\n

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Seal System<\/p>\n

PU \/ PTFE<\/p>\n

Quad-ring piston, \u221225 \u00b0C to +100 \u00b0C<\/p>\n<\/div>\n

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Port Standard<\/p>\n

BSP G3\/8″<\/p>\n

SAE ORB available on request<\/p>\n<\/div>\n

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Mounting Style<\/p>\n

Clevis \u00d7 2<\/p>\n

\u00d820 mm pin bore both ends<\/p>\n<\/div>\n<\/div>\n

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Push Force (Extend)<\/p>\n

39.4 kN<\/p>\n

F = 160 bar \u00d7 \u03c0\/4 \u00d7 56\u00b2<\/p>\n<\/div>\n

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Pull Force (Retract)<\/p>\n

8.7 kN<\/p>\n

F = 160 bar \u00d7 \u03c0\/4 \u00d7 (56\u00b2\u221250\u00b2)<\/p>\n<\/div>\n

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Push \/ Pull Ratio<\/p>\n

4.53 : 1<\/p>\n

Chopper engagement demands high push force; spring-return handles retract \u2014 this ratio is deliberate, not a compromise.<\/p>\n<\/div>\n<\/div>\n

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\"Corn<\/p>\n

The chopper system runs continuously during harvest \u2014 its hydraulic actuator must hold position against blade-strike vibration for hours at a stretch<\/p>\n<\/div>\n

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Corn Harvester Chopper Cylinder 56mm Bore 50mm Rod \u2014 Why This Specification Exists and What Happens When It Is Wrong<\/h2>\n

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Q<\/div>\n
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Why does a 130 mm stroke chopper cylinder need a 50 mm rod \u2014 the same diameter as the 300 mm stroke header lift cylinder?<\/p>\n

Stroke length does not determine rod diameter \u2014 load case<\/em> does. The chopper cylinder operates in a sustained high-vibration environment: the rotating blade shaft runs at 1,200\u20131,800 RPM directly adjacent to the cylinder mounting bracket, and blade-on-stalk impacts generate repeating impulsive lateral loads through the chopper frame into the cylinder pivot. A slender rod on a short-stroke cylinder in this position will develop fretting wear at the piston seal and gland under these lateral micro-cycles, not under conventional push-pull loading. The 50 mm rod provides the lateral bending stiffness to prevent rod deflection amplitudes that would accelerate seal fretting \u2014 a failure mode that a buckling calculation alone will not reveal because it is fatigue-driven, not static.<\/p>\n<\/div>\n<\/div>\n

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Q<\/div>\n
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The push\/pull ratio is 4.53:1 \u2014 isn’t that an extreme asymmetry? What does it mean in practice?<\/p>\n

It is extreme for a positioning cylinder, but it is correct for a chopper engagement actuator. Here is the mechanism: the cylinder pushes the chopper counter-knife mounting rail against its operating spring preload to set blade-to-counter-knife clearance. This requires 39.4 kN because you are compressing multiple return springs simultaneously while overcoming friction in the adjustment rail guides. Once the position is set, the cylinder holds \u2014 it is not continuously cycling. When the operator releases or opens the gap, the spring system provides the retract force \u2014 the hydraulic pull of 8.7 kN simply controls the rate of retraction, it does not need to overcome the spring alone.<\/p>\n

Trying to use a standard 56\/32 mm rod cylinder here \u2014 which would give a push\/pull ratio closer to 1.75:1 and only 22.5 kN push force \u2014 would result in the cylinder being unable to compress the counter-knife spring system to the minimum clearance position. The machine would appear to operate but with an excessive blade-to-counter-knife gap, leading to poor stalk chopping quality and elevated whole-stalk rejection rate.<\/p>\n<\/div>\n<\/div>\n

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Q<\/div>\n
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The surge pressure rating is 250 bar \u2014 what is causing pressure surges on a position-holding cylinder?<\/p>\n

Blade strikes. When a corn stalk contains a buried stone, an embedded metal fragment from previous tillage, or a dense knot section, the rotating chopper blade impacts it with an energy spike that transmits directly through the blade shaft and frame into the counter-knife mounting. If the counter-knife is hydraulically positioned, that impact energy partially translates into a hydraulic pressure spike in the rod-side circuit. On a short-stroke, high-bore cylinder, the hydraulic stiffness (pressure rise per unit displacement) is very high \u2014 a 2 mm rod-side displacement at 50 mm rod, 130 mm stroke generates a pressure spike of several tens of bar above circuit pressure. The 250 bar surge rating is not theoretical headroom: it is the calculated peak from a stone-strike event modelled against the circuit’s relief valve response time. Any cylinder rated below 200 bar surge on this position is inadequately specified.<\/p>\n<\/div>\n<\/div>\n

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Q<\/div>\n
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Why is the internal leakage specification tighter here than on the grain tank lift cylinder?<\/p>\n

Chopper blade-to-counter-knife clearance is typically set within a range of 1\u20135 mm. The operational consequence of exceeding the upper limit by even 2 mm is measurable: stalk particle length increases, the proportion of whole-stalk carryover to the field rises, and in markets where straw quality matters for subsequent soil incorporation, agronomic performance degrades visibly. An internal leakage rate above 5 cc\/min on the rod-side port of this cylinder translates to approximately 0.3 mm\/min gap increase under the counter-knife spring load. Over a 30-minute field section without readjustment, that is a 9 mm drift \u2014 enough to take the machine from optimum to poor chopping quality. The \u2264 3 cc\/min specification is tighter because the application demands it, not because it is a standard production specification applied universally.<\/p>\n<\/div>\n<\/div>\n

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Stalk Chopper Hydraulic Cylinder \u2014 Construction Detail and Material Standards<\/h2>\n
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Cylinder Tube<\/p>\n

E355 cold-drawn seamless, honed to Ra \u2264 0.4 \u00b5m. Wall 7 mm \u2014 calculated for 4:1 yield safety at 250 bar. External: zinc phosphate + PU topcoat, 500-hour salt spray.<\/p>\n<\/div>\n

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Chromstange<\/p>\n

Ck45 steel, ground Ra \u2264 0.2 \u00b5m. Hard chrome 25\u201330 \u00b5m, HV 800+. Post-plate ground to h6. At 50 mm \u00d8, I = 307,000 mm\u2074 \u2014 lateral stiffness that matters in high-vibration mounting positions.<\/p>\n<\/div>\n

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Piston & Seals<\/p>\n

Cast iron piston, double PTFE guide rings. Primary seal: PU quad-ring + PTFE backup. Rod seal: dual-lip PU. Wiper: PU with steel exclusion lip. Full seal kit available separately as catalogued spare.<\/p>\n<\/div>\n

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End Fixings<\/p>\n

Clevis both ends, \u00d820 mm pin bore, sintered bronze self-lubricating bush. Grease nipple at each pivot. Clevis wall 14 mm machined steel \u2014 rated for lateral bending moments from vibration loading.<\/p>\n<\/div>\n

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QC Protocol<\/p>\n

Hydrostatic proof test 250 bar \u00d7 60 s per unit. Full-stroke cycle \u00d7 5 under rated load. Leakage check both ports. Dimensional audit: C\/C, stroke, pin bore. Records retained per batch.<\/p>\n<\/div>\n<\/div>\n

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\"Corn<\/p>\n

Chopper quality \u2014 stalk particle size and uniformity \u2014 is directly determined by the blade gap the hydraulic cylinder holds<\/p>\n<\/div>\n

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Platform Fit and Fitment Verification<\/h2>\n

The YM4P.83.01 is OEM-specified for the YM4P 4-row corn harvester chopper mechanism. For distributors cross-referencing this part against other platforms, the following dimensional checks govern correct fitment:<\/p>\n

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C\/C Retracted<\/p>\n

390 mm<\/p>\n

Primary bracket-match dimension. Measure existing cylinder before ordering.<\/p>\n<\/div>\n

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Pin Bore<\/p>\n

\u00d820 mm<\/p>\n

Both clevis eyes. Verify pin diameter on machine before ordering.<\/p>\n<\/div>\n

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Rod Diameter<\/p>\n

50 mm<\/p>\n

Do not substitute a thinner rod \u2014 see engineering rationale above.<\/p>\n<\/div>\n

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Port Thread<\/p>\n

BSP G3\/8″<\/p>\n

SAE ORB available; specify at order.<\/p>\n<\/div>\n

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Stroke<\/p>\n

130 mm<\/p>\n

Custom strokes 100\u2013160 mm available on inquiry.<\/p>\n<\/div>\n<\/div>\n

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Stalk Chopper Blade Gap Hydraulic Cylinder \u2014 Custom Configurations for OEM Integrators<\/h2>\n

Standard YM4P.83.01 is stocked for direct replacement supply. OEM integrators developing platform-specific chopper mechanisms can specify the following without tooling surcharge at qualifying order volumes:<\/p>\n