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Crossplane
The crossplane or cross-plane is a crankshaft design for piston engines with a 90° angle (phase in crank rotation) between the crank throws. The crossplane crankshaft is the most popular configuration used in V8 road cars.[citation needed]
Aside from the V8 already mentioned, other examples of configurations using such 90° piston phases include straight-2, straight-4, V2, and V4 engines.
Crossplane crankshafts could feasibly be used with a great many other cylinder configurations, but the advantages and disadvantages described below may not apply to any or all of them and must be considered on a case-by-case basis.
The most common crossplane crankshaft for a 90° V8 engine has four crankpins, each serving two cylinders on opposing banks, offset at 90° from the adjacent crankpins. The first and last of the four crank pins are at 180° with respect to each other as are the second and third, with each pair at 90° to the other, so that viewed from the end the crankshaft forms a cross.
The crankpins are therefore in two planes crossed at 90°, hence the name crossplane. A crossplane V8 crankshaft may have up to nine main bearings in the case of an eight throw design, and usually has five bearings supporting four throws each with a shared crank pin.
The crossplane design was first proposed in 1915, and developed by Cadillac and Peerless, both of whom produced flatplane V8s before introducing the crossplane design. Cadillac introduced the first crossplane in 1923, with Peerless following in 1924.
The crossplane V8 was developed to produce a smoother engine than possible with a flatplane design. Because four pistons stop and start together in the same plane in both banks, the second-order forces inherent to the flatplane design stack up and become noticeable in large displacement engines. Each bank of the crossplane engine has four distinct piston phases that cancel the second-order free forces entirely, leaving only minor vibrations due to variation in masses of components during manufacture.
However, the 180° disposition of the end and middle crank throws does result in a primary (crank speed) rocking couple, which in the 90° V case can be countered by weighting the crankshaft appropriately, much like a V-Twin. Other V-angles generally require a balancer shaft to keep things as smooth.
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Crossplane
The crossplane or cross-plane is a crankshaft design for piston engines with a 90° angle (phase in crank rotation) between the crank throws. The crossplane crankshaft is the most popular configuration used in V8 road cars.[citation needed]
Aside from the V8 already mentioned, other examples of configurations using such 90° piston phases include straight-2, straight-4, V2, and V4 engines.
Crossplane crankshafts could feasibly be used with a great many other cylinder configurations, but the advantages and disadvantages described below may not apply to any or all of them and must be considered on a case-by-case basis.
The most common crossplane crankshaft for a 90° V8 engine has four crankpins, each serving two cylinders on opposing banks, offset at 90° from the adjacent crankpins. The first and last of the four crank pins are at 180° with respect to each other as are the second and third, with each pair at 90° to the other, so that viewed from the end the crankshaft forms a cross.
The crankpins are therefore in two planes crossed at 90°, hence the name crossplane. A crossplane V8 crankshaft may have up to nine main bearings in the case of an eight throw design, and usually has five bearings supporting four throws each with a shared crank pin.
The crossplane design was first proposed in 1915, and developed by Cadillac and Peerless, both of whom produced flatplane V8s before introducing the crossplane design. Cadillac introduced the first crossplane in 1923, with Peerless following in 1924.
The crossplane V8 was developed to produce a smoother engine than possible with a flatplane design. Because four pistons stop and start together in the same plane in both banks, the second-order forces inherent to the flatplane design stack up and become noticeable in large displacement engines. Each bank of the crossplane engine has four distinct piston phases that cancel the second-order free forces entirely, leaving only minor vibrations due to variation in masses of components during manufacture.
However, the 180° disposition of the end and middle crank throws does result in a primary (crank speed) rocking couple, which in the 90° V case can be countered by weighting the crankshaft appropriately, much like a V-Twin. Other V-angles generally require a balancer shaft to keep things as smooth.