Recent Blogs
Hiscox’s 1,800 Mechanical Movements — Animated by FIRGELLI
An interactive companion to Gardner Dexter Hiscox’s Mechanical Movements, Devices and Appliances, with animations, engineering calculators, modern applications and a searchable index.
Dividing Head: Simple Indexing Calculator | FIRGELLI
Calculate crank turns, whole turns, hole-circle advance and ideal spindle step for simple indexing. Check whether the selected circle permits an integer hole move.
PUMA-Style Arm: Idealized 3R Wrist-Centre Kinematics
How a PUMA arm works — the 6-DOF articulated robot that defined modern industrial automation, from Unimation welding cells to lab automation today.
Drum Brake Mechanism Explained: How It Works, Parts, Diagram, Self-Energizing Action and Uses
Explore expanding shoes, wheel-cylinder pistons and return springs. Estimate brake torque from pressure, cylinder bore and supplied friction and shoe-force gain.
Disc Brake Mechanism: How It Works, Parts, Formula, and Real-World Uses Explained
Explore a single-piston floating disc brake. Calculate ideal pad force and braking torque from hydraulic pressure, piston diameter, friction and effective radius.
Locking Pliers: Over-Centre Link Geometry Explained
Explore a locking-pliers toggle and its main components. Calculate angle and axial projection for a selected local link length and past-center offset.
Oldham Coupling: Hiscox Items 1287–1288
Explore how an Oldham coupling bridges parallel shaft offset. Calculate ideal tongue travel, maximum sliding speed and the intermediate disc centre orbit.
Stillson Pipe Wrench: Applied Torque and Documented Jaw Action
How a Stillson pipe wrench works — the floating-jaw cam action, bite angle math, and real plumbing and pipefitting applications with sizing guidance.
Watt Straight-Line Linkage: Animation and Path Calculator | FIRGELLI
Explore a Watt four-bar, vary link lengths and input sweep, and compare approximate straight-line travel with the actual sampled lateral deviation.
Cam-operated Shears Mechanism Explained: How It Works, Diagram, Parts, Force Formula and Uses
See a cam close a pivoted shear. Estimate cutting-edge force for a solid round section and compare cycle timing, with clear limits on cam-load and...
Valve-motion Eccentric: Ideal Projection and Speed Calculator
Calculate the ideal projection of a rotating eccentric center from throw, crank angle, advance and shaft speed. Actual strap, rod and valve motion are not...
Disc Valve for Large Gas Pipes: Port Alignment, Gear Drive and Geometry Calculator
Explore a pinion-driven ported disc valve. Calculate geometric port overlap and an ideal covered-port pressure force using an illustrative four-port layout.
Counter-weighted Gas Holder Mechanism: How It Works, Parts, Formula and Calculator
Explore a water-sealed gas holder with two counterweights. Calculate the ideal static pressure balance and whether the entered bell mass needs counterweights or ballast.
Chain and Pulley (Form 3): Inward-toothed Chain, Notched Wheel and Reference Calculations
Explore an inward-toothed chain engaging a notched wheel. Compare static force under an equal-contact assumption and a measured pitch difference against an entered tolerance.
Four-pulley Two-speed Drive: Ideal Ratio Comparison
Compare two ideal no-slip speed ratios and their paired pitch-diameter sums. Equal diameter sums alone do not establish that the same belt fits both positions.
Recording Watt-hour Meter Mechanism Explained: How the Ferraris Induction Disc Works, Parts & Uses
See how an induction watt-hour meter works. Calculate real power, energy, ideal disc speed and disc turns from voltage, current, power factor, time and Kh.
Electric Brake Mechanism: How It Works, Diagram, Parts, Holding Torque Formula and Uses
See how springs apply a disc brake and an energized coil releases it. Compare static holding torque from clamp force, friction radius and active faces.
Direct-connected Vertical Compound Engine: How It Works, Parts, Diagram & Uses in Power Stations
Explore a vertical compound engine and directly connected generator. Compare cylinder swept volumes, area ratio, connecting rod length and crank phase.
Bipolar Shunt Generator Mechanism: How Self-Excitation Works, Diagram, Parts and Uses Explained
Explore a two-pole shunt generator and its fixed-speed, no-load voltage equilibrium. Adjust the magnetization curve and field resistance to compare voltage, current and field power.
Gamma Stirling Engine: Animation, Geometry and Timing Calculator
Explore separate displacer and power cylinders. Calculate power-piston stroke, swept volume and cycle timing while comparing crank radii and phase.
Beta Stirling Engine: Animation and Geometry Calculator | FIRGELLI
Explore the displacer and power piston in one cylinder. Calculate both strokes and power-piston swept volume while varying crank geometry and phase.
Solid End Connecting Rod Mechanism Explained: How It Works, Diagram, Parts, Uses, and Calculator
Solid end connecting rod explained — how the closed big-end works, why early gas engines used it, sizing math, and worked example for stationary engine...
Wooden Road Bridge Truss: Ideal Support-reaction Calculator
Place one point load along a simply supported span and calculate left and right reactions. Truss member forces, timber capacity and bridge safety are not...
Suspension Bridges Mechanism: How Cable Tension, Towers, and Anchorages Work — Diagram & Calculator
See how suspenders, cables, towers and anchorages carry bridge loads. Explore ideal main-cable tension from span, load and sag with a statics calculator.
Shears with Winch or Tackle Block: How It Works, Diagram, Formula & Rigging Uses Explained
How a shears lifting rig works — the geometry, the tackle block math, and how riggers use it to set heavy loads on bridges, masts,...