What a lock drive gear transfers from actuator to mechanism
Review this component together with its mating parts and delivered condition. The interfaces below define the drawing information needed to assess forming, finishing and inspection.
The gear drawing must distinguish tooth geometry from the surrounding lock components.
Tooth data, mating gear and driven-connection interfaces
Provide tooth data, the mating gear and the driven connection.
Include motor or manual input duty, reversal and stop conditions.
Why include reversal and stop conditions for a lock gear?
A lock drive can operate over a limited movement rather than continuous rotation.
Its defined duty therefore needs to identify how it starts, reverses and stops.
That context supports an appropriate manufacturing and acceptance discussion for the actual gear.
PM versus gear machining for lock gear profiles
Compare PM and gear machining for the actual profile and quantity.
The lock assembly photograph is context, not a specification for the gear blank or material.
The proposed route is confirmed for your drawing, material and quantity. An image does not establish a fixed tolerance or a complete process specification.
Compare manufacturing capabilities →Lock drive gear material, treated-surface and corrosion requirements
Specify the base material, final condition and corrosion or appearance requirements.
Mark drive, guiding and contact surfaces that must meet their dimensions after treatment.
The component specification does not establish a security rating for the complete lock.
Review material-selection information →Tooth, mounting fit and lock-action engagement checks
Check teeth, mounting fit and engagement under the agreed lock action.
Evaluate any backlash or stop-load requirement with the mating drive.
Specify the drawing revision and the condition in which each dimension is inspected. Record the agreed dimensional and functional checks before sample approval.
Quality documentation →How PM lock drive gears fail: tooth root, bore and drive connection
A lock drive gear sits downstream of a motor or a thumb, and it is loaded in the least forgiving way: intermittent, reversing, and often stalled against a dead stop. The three places it gives up are the tooth root, the bore on the shaft, and the drive connection.
| What goes wrong in service | What drives it | Where the drawing closes it out |
|---|---|---|
| A tooth shears at the root when the mechanism stalls | Density is not uniform in a compacted part. If the root radius is small and the density at the root is lower than at the flank, the root is the weakest section in a load path that is designed to stall against a stop. | Root radius called out as a controlled feature rather than as a drawing artefact, plus the density requirement located at the tooth region; verified by a stall-torque test to failure and by metallographic density measurement at the root. |
| The drive whines at one point per revolution | Noise that repeats once per turn is usually a concentricity or pitch problem rather than a tooth-form problem: the bore and the tooth ring are not sharing an axis as well as the profile suggests. | Concentricity of the tooth ring to the bore stated separately from total profile tolerance, plus the mating gear identified; verified on a rolling fixture against a master gear rather than by measuring single-profile points. |
| The bore wears oval on the shaft | A porous bore running on a hard shaft with marginal lubrication wears by abrasion and then by embedding. Ovality, once started, feeds itself because the contact area keeps shrinking. | Bore density and bore finish stated, along with the mating shaft hardness as a pair; verified by a run-in test on an assembled mechanism and a bore roundness check afterwards, not before. |
| The gear spins on the shaft flat | The drive is a D-flat or a spline formed in the bore, and its depth and corner radius are usually left as tooling details. Under stall torque the flat crushes and the gear slips. | Flat depth, position and corner radius called out, plus the drive torque the connection must carry; verified by a slip test at the stated torque on the assembled gear and shaft. |
| The end face galls against the housing | End faces are often the last thing to be considered, and they run against die-cast or sheet surfaces with no lubrication. Flatness and the burr left where the teeth exit the face decide whether it rubs evenly or digs in. | Face flatness and a burr condition at the tooth exit stated, plus which face is the running face; verified by running the gear against a production housing and inspecting the contact pattern. |
Note. The table names service failure modes and the drawing features that address them; it sets no acceptance values. Dimensions, tolerances and test criteria come from the project drawing.
The root and the drive flat are geometry that the compaction tool decides, so they are worth arguing about at tool design, not at first article. The bore and the running face are process-dependent, because density and burr are set by compaction pressure and by how the tool is maintained. Noise is the item that cannot be resolved by either party alone: it needs the mating gear named on the drawing, because a gear that is perfect on its own can still whine against the part it was never matched to.
Prepare a Product-Specific RFQ
- Component definition. Send the 2D drawing and 3D model, where available, with the drawing revision and the requested part or assembly scope.
- Mating information. Include the assembly references needed to define the interfaces discussed above.
- Delivered condition. State material, finishing and inspection requirements, identifying any items that need a manufacturing recommendation.
- Supply plan. Include sample needs, expected order and annual quantities, packaging requirements and target timing.
Product Questions
Can the surrounding lock assembly photo define the gear?
No. The gear needs its own tooth, mounting and material specification even when the assembly is known.
Why include reversal and stop conditions for a lock gear?
A lock drive can operate over a limited movement rather than continuous rotation. Its defined duty therefore needs to identify how it starts, reverses and stops. That context supports an appropriate manufacturing and acceptance discussion for the actual gear.
How should the completed mechanism be checked?
Check teeth, mounting fit and engagement under the agreed lock action. Evaluate any backlash or stop-load requirement with the mating drive.
Technical Context
The product-specific notes above identify drawing-review questions. General process and material references are collected separately; they do not verify a material grade, production qualification or performance claim for the pictured part.
Manufacturing and material references →