Read gear diagrams in ManYue: check common-view direction separately from tooth ratios

Three pictured gears do not establish a familiar connection automatically. Read a diagram with stated external meshes and tooth counts in ManYue, checking each contact before calculating revolutions from a given input. This is idealised diagram reading, without running or building machinery or treating comic strokes as measured torque, capacity or manufacturability.

State the transmission assumptions first

Record work, edition, page, panel and caption. A has twelve teeth, B twenty-four and C twelve, on fixed parallel axes. A externally meshes with B, B with C, and A does not contact C; assume ideal motion without skipped teeth. View all from the same front, with A specified to turn clockwise twice. Counts are stipulated, not guessed from blurred teeth or schematic size. Without stated contacts or counts in a real comic, retain visible structure and unknowns rather than applying these results. Proximity does not prove engagement.

Reverse direction at each external mesh

With A clockwise, B is counterclockwise in the common view; B drives C clockwise. Matching endpoint directions follow from two reversals, not their equal tooth counts. Write A-to-B and B-to-C separately rather than making every neighbouring gear clockwise. Viewing from the opposite side changes clockwise descriptions, so normalise viewpoint first. Internal gears, belts, worms and compound coaxial gears require their own rules; the external-mesh chain is not universal.

Use tooth passage to check revolutions

Twelve tooth pitches pass the contact per A revolution, so two revolutions correspond to twenty-four pitches. B has twenty-four per revolution and therefore turns once, counterclockwise. This is ideal correspondence, not teeth passing through solid material. Do not mistake twelve divided by twenty-four for a claim that B also turns twice, or replace stated counts with drawn diameters. If using a ratio, identify numerator and denominator. Here use A revolutions times A teeth equals B revolutions times B teeth, avoiding conflicting ratio conventions.

Check the idler-to-output relation

One B revolution corresponds to twenty-four tooth pitches, so twelve-tooth C turns twice, clockwise. Equal A and C revolutions do not mean B remains still: it turns once. Nor does an idler never affect anything. In this simple ideal external train with one gear per shaft, its tooth count cancels from the endpoint revolution ratio. That cancellation proves no spacing, load capacity or perfect efficiency and does not establish lossless transmission of arbitrary force.

Retain assumptions when changing the idler

For a paper control replace B with thirty-six teeth, explicitly maintaining valid external meshes and allowing axis positions to adjust. Two A revolutions give two-thirds of a B revolution and still two C revolutions. The endpoint ratio remains while B’s motion changes. Do not alter counts in a fixed-centre real arrangement without checking geometry and promise it fits. This demonstrates an ideal relation, not a machinery modification. If B’s shaft carries another differently toothed gear driving C, it is compound gearing and the simple cancellation no longer applies.

Keep revolutions separate from rates

The main sample gives two A revolutions without elapsed time, so one B and two C revolutions are not revolutions per minute. If a separate steady input is thirty A revolutions per minute, the same ideal relation gives fifteen for B and thirty for C, retaining units for each. Two motion strokes are not two revolutions, and ten seconds of reading are not ten seconds of operation. A still image alone need not establish direction; arrows or text supply that premise. Without time, stop at revolution relations rather than inventing rates or acceleration.

Check viewpoint and obscured connections

When results disagree, check labels, external-mesh pairs, common viewing side and input identity before counts or extra coaxial gears. Mark hidden connections unknown instead of inventing a rear belt to force agreement. Where drawn teeth are abbreviated, use explicitly stated counts rather than every visible point. If drawing and labels genuinely conflict, preserve both rather than edit the work. A short location record and your ledger suffice for discussion; neither running machinery nor copying the book is needed. No automatic simulator is required for the manual check.

Leave and return to check direction, turns and units

Leave reading and return to the diagram. Follow clockwise, counterclockwise, clockwise from A through B to C and recalculate two, one and two turns. Check the thirty-six-tooth control’s two-thirds turn and the rate control’s fifteen per minute. Retain identity, mesh assumptions, counts, viewpoint, input/output and unknown conditions. Each conclusion must trace to a connection and given quantity, not prove actual machinery works or automatic gear detection. Recheck internal meshes, compound gears and changed views instead of treating this chain as unconditional.

Related guides and sources

ManYue: Separate part identifiers from assembly-step numbers in exploded views; ManYue pictured balances: establish equal arms and static conditions before comparing pans.

Checked on November 12, 2026: Apple public information lists ManYue 2.0.5, requiring iOS / iPadOS 15.0 or later. See the official App Store for published capabilities; verify specific controls in the installed version.

Method reference: LEGO Education: meshing gears, direction and idler gears. Samples, passages and controls are original exercises. Sources establish definitions and checking methods rather than new automatic analysis in the app. Manual records may be kept externally, and unknown fields should remain explicit. This article does not claim step-by-step testing on a physical device, private server or every output environment.