A stationary oil cup supplies a revolving pipe aligned with the crankshaft axis. The pipe turns with the crank and leads out to the crank-pin oilway. A sliding support allows the fixed supply to be aligned with the rotating inlet. The animation follows the arrangement in Hiscox figure 323.
Separate actuator applications
The crank drives the revolving feed pipe; a linear actuator is not part of this oiling arrangement. Its pressure calculation does not size an actuator or establish oil delivery to a bearing.
For a separate positioning task, compare actual load, stroke and mounting requirements with the FIRGELLI actuator specifications. Moving equipment needs its own guides and supports; those details are separate from the rotating-pipe model shown here.
Centrifugal Crank-pin Oiler Interactive Calculator
Vary crank speed, crank-pin radius and oil density. Watch the connected feed pipe rotate, then compare angular speed, radial acceleration, ideal oil head and centrifugal pressure rise.
Equation Used
- A full passage with oil co-rotating at the crankshaft angular speed.
- Feed begins at zero radius; the outlet is at the entered crank-pin radius.
- Constant density and speed; no transient filling or delivery-rate calculation.
- The animation omits the bearing housing and connecting rod to reveal the pipe. Dimensions other than crank radius are illustrative.
This is the stationary-cup and revolving-pipe arrangement in Hiscox figure 323. The calculator estimates ideal centrifugal pressure in a full rotating passage; it does not predict oil flow or bearing lubrication requirements.
Fixed supply, rotating feed pipe
Hiscox figure 323 shows an oil cup on an adjustable sliding support. Its outlet aligns with the crankshaft axis, allowing the feed pipe to revolve while the supply remains stationary. The bent pipe extends outward to the crank pin and rotates with the crank.
The animation separates the fixed cup and stand from the rotating web and pipe. The blue bore shows a continuous route from the axial inlet to the crank-pin oilway. The support clamp stays fixed throughout the cycle.
The adjacent figure 324 shows a different oiler with an annular rotating cup. In the figure 323 arrangement illustrated here, the cup stays fixed and feeds a revolving pipe. The drawing explains that connection without specifying manufacturing dimensions or oil delivery rate.
Reading this historical crank-pin oiler
The mechanism addresses the connection between a stationary oil supply and a rotating crank pin. Its defining features are the adjustable supply support, axis-aligned revolving inlet and pipe leading to the pin.
The illustration is useful for understanding that connection and the effect of rotational speed on ideal centrifugal pressure. It does not establish a particular engine manufacturer, installation date, oil grade, refill interval or bearing-duty limit.
Centrifugal head and pressure
For steady rotation, angular speed is ω = 2πN/60 rad/s. Radial acceleration at distance r is a = ω²r. In a full co-rotating oil passage, the centrifugal pressure gradient is dp/dr = ρω²r.
Integrating from the shaft axis to radius r gives Δp = ρω²r²/2. The equivalent oil head is h = Δp/(ρg) = ω²r²/(2g). For an inlet at a nonzero radius r₀, the corresponding term would be r² − r₀²; this calculator assumes r₀ = 0.
Doubling speed or radius multiplies head and pressure by four. Density changes pressure, but cancels from the equivalent oil-head expression. Acceleration grows with radius rather than its square.
Pressure potential alone does not give a flow rate. A delivery calculation would also need passage geometry, oil viscosity, inlet conditions and bearing resistance. Gravity can also contribute as the crank changes position; it is excluded from the centrifugal-only results.
Example: 180 rpm and 120 mm crank radius
At N = 180 rpm, r = 0.120 m and oil density 870 kg/m³, angular speed is 18.8496 rad/s. The radial acceleration is 42.6367 m/s², or about 4.348 g.
The equivalent centrifugal head is 0.26086 m of oil, and pressure rise is 2225.64 Pa. Halving speed to 90 rpm reduces both head and pressure to one quarter: about 65.21 mm and 556.41 Pa.
These numbers do not establish a drip rate, a suitable orifice diameter or an acceptable bearing temperature. They isolate the centrifugal contribution to pressure for the stated assumptions.
What the model does and does not establish
The calculator relates speed, radius and density to ideal centrifugal pressure. Oil delivery rate requires a separate flow model using the passage and bearing conditions.
An actual lubricating system also depends on oil supply, alignment, leakage, passage condition, viscosity and bearing requirements. Those properties cannot be inferred from the three sliders. In particular, zero centrifugal pressure at zero rpm does not mean that gravity cannot move oil.
Calculator questions
Why does the oil cup stay still?
This arrangement supplies oil from a stationary cup into a revolving pipe aligned with the shaft axis. The pipe and crank rotate together; the cup and its adjustable support do not.
Why does density change pressure but not oil head?
Pressure is proportional to density. Head is pressure divided by density times gravity, so density cancels in this ideal centrifugal calculation.
Does the blue pipe animation show the oil delivery speed?
No. It identifies the filled passage and its mechanical rotation. The calculator has no model for volumetric flow through that passage.
What happens at zero rpm?
The crank stops and the centrifugal head, pressure and acceleration become zero. Gravity-driven feed is outside this calculation and may still occur in an actual installation.
References & Further Reading
- Gardner D. Hiscox, Mechanical Movements, Powers, Devices and Appliances (1901), printed page 90, figure 323: stationary oil supply, adjustable support and revolving feed pipe.
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