Electrification & Early Modern (1870–1920)Fluid Mechanics & Hydroelectric Turbines

Pelton Split-Bucket Impulse Water Turbine

US 233,692

Bifurcated Double-Cup Buckets with Central Knife-Edge Splitter and 170-Degree Flow Reversal

Inventor(s)Lester Allen Pelton

Grant Date1880-10-26

Filing Date1880-07-03

LocationCamptonville, Yuba County, California

The 1880 hydroelectric breakthrough that powers high-head water generation: Lester Pelton's split-bucket impulse wheel featuring double-cup buckets divided by a sharp central splitter wedge that bifurcates high-pressure water jets and turns the flow through nearly 180 degrees, transferring over 90 percent of the water's kinetic energy into rotational shaft power.

USPTO PDF

Engineering Analysis & Physical Principles

How It Works: Step-by-Step Mechanical & Physical Breakdown

During the California Gold Rush, miners in the Sierra Nevada mountains needed immense power to crush hard quartz gold ore. Flat-paddle water wheels (called 'hurdy-gurdy' wheels) were terribly inefficient ( efficiency): the water jet hit the flat cup, splashed out chaotically in all directions, and left the wheel carrying half of its kinetic energy. Lester Pelton discovered that if a bucket is shaped as a double cup with a sharp knife-edge splitter down the middle, the water jet is divided into two smooth sheets and turned through nearly , dropping its exit velocity to zero and capturing over of the water's kinetic energy.

The Core Breakthrough Mechanism

A high-pressure water nozzle fed from a high alpine penstock shoots a concentrated jet of water at supersonic or high hydraulic velocity (). As each bucket rotates into position, the central knife-edge splitter cleanly divides the circular water jet into two equal halves. Each half-stream flows smoothly around the curved cylindrical side cup, turning through relative to the moving bucket. Because the wheel is geared to spin at exactly half the speed of the jet (), the water emerges from the sides with an absolute forward velocity of nearly zero (), falling gently away into the tailrace by gravity.

Interactive Real-Time Physical Simulation

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INITIALIZING THREE.JS WEBGL SIMULATION...

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Impulse Hydrodynamics & Momentum Transfer

Jet Velocity

94 m/sv_jet[1]

Turbine Efficiency

93%eta[1]

Turbine Shaft Power

185 kWP_hydro[1]

Hydraulic Water Head450 m

Runner Rotational Speed600 RPM

Interval ghosts

η93.0 % · [40, 93]

Fidelity / MMS residual

Impulse speed ratio u/v

model0.501

reference0.500

residual0.001

Dated scenarios

Detailed Component Architecture

1Bifurcated Double-Cup Bucket Geometry

Twin ellipsoidal concave bowls separated by a central knife splitter.

Cast from high-strength bronze or forged steel. The central splitter has a sharp edge () and an entrance angle to prevent shock stagnation pressure, splitting the stream into two balanced lateral sheets.

19th-C. Term: Two concave curved cups separated by a central splitterModern: Pelton split-cup runner bucket / Double-hemispherical bucket

2High-Pressure Impinging Needle Nozzle

Convergent spear nozzle producing a solid, non-diverging water jet.

A convergent circular nozzle with a central adjustable aerodynamic spear needle. Regulating needle axial position dynamically throttles the jet cross-sectional area () while maintaining full velocity head () at partial loads.

19th-C. Term: Nozzle arranged to direct a jet of waterModern: Pelton spear nozzle / Variable-needle injector

3Peripheral Runner Disk & Keyed Hub

Forged steel wheel disk mounting 20 to 24 perimeter buckets.

A heavy steel disk with precision CNC/milled lugs securing each bucket with high-strength shear bolts. Operating at tip speeds exceeding , the disk withstands centrifugal stresses and cyclic hydraulic impulse impacts.

19th-C. Term: Periphery of the wheel with double-cup bucketsModern: Pelton turbine runner / Impulse turbine wheel

4Bucket Entrance Cutout Notch

Angled lip notch permitting incoming bucket to enter jet without chopping the stream.

A parabolic cutout notch () machined into the leading lip of each bucket. As the bucket rotates into the jet path, the notch allows the water jet to impinge uninterrupted on the preceding bucket until the central splitter takes over smoothly, preventing parasitic back-splashing against the bucket underside.

19th-C. Term: Recess in the front lip of the bucketModern: Bucket entrance notch / Jet clearance cutout

5Emergency Jet Deflector & Servomotor Actuator

Fast-acting hydraulic shield slicing into the jet to protect against grid load dump.

A curved steel deflector blade pivoted between the nozzle tip and bucket perimeter. During sudden full electrical load rejection, a hydraulic servomotor flips the deflector into the jet path within , diverting the stream into the tailrace without closing the penstock needle suddenly and causing catastrophic water hammer ().

19th-C. Term: Deflecting shield for cutting off the streamModern: Jet deflector blade & hydraulic governor servo

Interactive Mathematical Physics & Rigorous Mechanics

Governing Equations & Colorized Principles

Dual-coded visual mapping & live SI telemetry

Euler Double-Cup Splitter Bucket Momentum Reversal & Peak Impulse Work

Hydrodynamics & TurbomachineryClaim 1

Mathematical Governing Law

Terms:

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The extracted from the equals relative speed between the and multiplied by the , achieving when bucket speed is exactly half the water jet speed.

F_{\text{bucket}}

Impulse Thrust Force

Mechanical force exerted on the rotating runner buckets by the deflected water jet

Newtons (N)[M L T^-2]

By curving the cup to reverse the water direction nearly 180 degrees (\beta \approx 165^\circ), \cos(165^\circ) \approx -0.966, so (1 - \cos\beta) \approx 1.966—doubling the force compared to a flat paddle (1.0).

Physical Principle & Engineering Insight

Lester Pelton watched a water jet hit a flat paddle in a California gold mine and noticed it merely deflected sideways. When an accidental misalignment caused the jet to hit a curved bucket rim and shoot backwards, the wheel spun twice as fast. Pelton patented the central splitter double-cup that extracts nearly 100% of water kinetic energy.

Historical Context: US 233692 is the premier impulse water turbine, driving high-head hydroelectric dams in mountainous regions worldwide.

Fluid Momentum Transfer & Euler Turbine EquationPrinciple 1

Reversing the water flow through yields , nearly doubling the thrust force compared to a flat impact cup where ().

Optimal Peripheral Speed Ratio (Zero Residual Kinetic Energy)Principle 2

When the bucket speed equals half the water jet speed, the relative exit velocity matches the forward motion of the bucket in the opposite direction, leaving the water stationary in space with zero wasted kinetic energy ().

Torricelli High-Head Jet HydrodynamicsPrinciple 3

Under alpine water heads of , water jet velocities exceed (), generating megawatt power densities in compact turbine housings.

Specific Speed & High-Head Hydraulic Efficiency RegimePrinciple 4

The low specific speed classification of the Pelton impulse turbine makes it thermodynamically superior to reaction turbines (Francis/Kaplan) for high hydraulic heads () with low volumetric flow rates.

Interactive Schematic Sheet (Fig. 1)

Drawing showing circular wheel perimeter, double-cup bucket cross-section, central knife-edge splitter, and impinging water jet trajectory.

1.00x

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Why It Still Matters

The Pelton wheel is the most efficient high-head water turbine in existence, operating at measured peak efficiencies exceeding . Pelton turbines generate high-pressure clean hydroelectric power across the Rocky Mountains, the European Alps, and the Himalayas, powering alpine regional power grids and pumped-storage energy systems worldwide.

Legal Claims Decoder (2 Numbered Claims)

Compare dense legalistic claims directly with decoded plain-English functional specifications.

Claim #1Independent Master Claim

1/2

Verbatim Historical Legal Text

“A water-wheel bucket comprising two concave curved cups separated by a central splitter wedge or ridge, substantially as described.”

Plain English Engineering Translation

Master pioneer claim: a water turbine bucket formed of two concave curved cups separated by a central splitter wedge or ridge to bifurcate water flow.

Key Protected Innovations:

Double-cup split bucket geometryCentral knife-edge water jet splitter180-degree flow reversal impulse extraction

Historical Legal Impact:

The landmark structural claim defining the Pelton water wheel, licensed and manufactured globally.

The Historical Bottleneck

In the 1870s, California gold miners used high-pressure water cannons ('monitors') for hydraulic mining. When they diverted this high-pressure water to drive wooden paddle wheels to run stamp mills, the flat buckets broke under the violent jet and wasted more than half the energy in wild splash-back.

Why Prior Art Failed

•Flat-cup 'hurdy-gurdy' wheels achieved barely 40% efficiency because water exited perpendicular to the wheel.
•Reaction Francis turbines required massive volumes of low-pressure water and were destroyed by abrasive silt and high-head pressures.
•Single-trough curved buckets pushed the wheel laterally and splashed incoming buckets.

The Breakthrough Insight

“In 1878 at Nevada City, California, Lester Pelton watched an ordinary curved bucket wheel when a mounting key slipped, misaligning the wheel so that the water jet struck the *edge* of the cup rather than the center. To his astonishment, the wheel suddenly sped up! Pelton realized that deflecting the water in a curved U-turn extracted twice the momentum, and immediately built a double-cup bucket with a central splitter.”

Patent Wars & Legal Litigations

Vs. 1883 University of California Turbine CompetitionInfringement Challenge

Rival Claim & Defense:

Rival California iron foundries (Knight, Collins, Risdon) claimed their flat and single-curved water wheels were superior.

Litigation Conflict:

In 1883, the University of California conducted exhaustive comparative dynamometer efficiency tests on all competing water wheels in Berkeley, California.

Final Resolution & Judicial Outcome:

Pelton's split-bucket wheel achieved an unprecedented efficiency of 90.2%, completely crushing all rivals (which tested at 60% to 65%). The Pelton Water Wheel Company in San Francisco immediately took over the global mining and hydroelectric market.

After the Grant

Pelton sold his patent and business rights in 1888 to the Pelton Water Wheel Company in San Francisco, receiving substantial royalties that allowed him to retire comfortably in Oakland, California. In 1895, Pelton was awarded the Elliott Cresson Medal by the Franklin Institute for his monumental contribution to hydraulic engineering.

Civilizational Impact

Pelton wheels powered the earliest electric power stations in the American West (such as the 1895 Folsom Powerhouse delivering high-voltage AC to Sacramento, 22 miles away). They enabled the electrification of mines, factories, and alpine rail networks across the world.

Historical Fact

Lester Pelton was a mild-mannered Ohio carpenter who joined the 1849 California Gold Rush. Finding little gold in panning, he built mining flumes and water wheels in Camptonville, California, testing his prototype double-cup buckets in a converted wooden butter churn using water piped from a local creek!