Curved Rack and Pinion Gear | Arc Segment Rack, Stainless Steel, Custom OEM

A curved rack follows an arc of defined radius. The pinion rolls along this arc exactly as it would along a flat rack — the involute tooth form ensures correct mesh geometry at any point along the arc, provided the centre distance between pinion axis and rack pitch circle is maintained. The angular displacement of the load is proportional to the arc length traversed, which is equal to the pinion pitch circle circumference multiplied by the angle of pinion rotation.

The key design parameters for a curved rack drive are: module (determines tooth size and load capacity), arc radius (determines the motion path curvature and the relationship between pinion turns and output angle), subtended arc angle (determines the total angular travel available), and face width (determines contact area and load capacity alongside module). The pinion is a standard spur or helical gear of matching module and pressure angle — no special pinion is required for the curved rack, only the rack itself is bent to the required radius.

Material choice for curved racks follows the same principles as flat racks: stainless steel for corrosion resistance in robotic, food-processing, or medical applications; C45 or alloy steel with carburized or induction-hardened teeth for high-load and high-cycle industrial applications; POM or nylon for light-duty, low-noise, and lubrication-free applications. The bending process that forms the arc must not introduce residual stress concentrations at the tooth roots — Ever-Power curved racks are machined to the arc geometry from solid rather than bent from flat stock, ensuring uniform tooth root strength around the full arc.

⚙ Precision Arc Geometry

The 70° V-shaped guide surface and cylindrical contact surface are finished to high surface quality. High finish, low noise, and accurate arc geometry ensure the guide system provides stable and repeatable angular motion without binding or chatter at any point along the arc.

🎯 High-Precision Positioning

Repeatable positioning accuracy to 0.03 mm is achievable when paired with a servo motor drive and closed-loop encoder feedback. The scientific positioning method is matched to the working environment — absolute encoders or linear scale feedback may be added for applications requiring better than 0.05 mm arc-path accuracy.

🔗 Multiple Connection Methods

Arc rack sections can be linked end-to-end with chain connection, belt drive, or linkage rod arrangements to achieve extended arc travel or synchronised multi-axis motion in circulation line systems. The half-tooth machined end faces maintain pitch continuity at every arc joint.

🤖 Intelligent and Automated Operation

Curved rack drives integrate directly with servo controllers and PLC motion programs. The required arc motion conditions are set once in the controller; the drive operates autonomously to improve efficiency, reduce manual labour, and lower per-cycle cost in automated assembly and inspection lines.

🔧 Easy Maintenance with Auto-Lubrication

The arc guide rack is compatible with standard automatic lubrication systems — a metered oil injector supplies the tooth flanks at every cycle, keeping the mesh lubricated without manual intervention. This dramatically extends service intervals in high-cycle applications such as 24-hour automated assembly lines.

♾ Split Open-and-Close Arc Configuration

Full-circle arc racks can be split into two 180-degree half-circles that open and close like a clamp. This design eliminates the need to thread the arc rack from the end of a long pipe or tube — the rack opens, clamps around the pipe at the required position, and closes for operation. Essential where both pipe ends are inaccessible.

Step 1 — Raw Material

Raw material bar stock verified by spectrochemical analysis before production.

Step 2 — Tooth Cutting

Teeth cut on CNC rack milling or hobbing machine to specified module and pressure angle.

Step 3 — Deburring

Tooth-end burrs removed and edges chamfered to prevent handling damage and sharp corners.

Step 4 — Straightening / HT

Pressure straightening after tooth cutting; induction hardening or carburising where specified.

Step 5 — End Machining

End faces and mounting holes machined in CNC machining centre to drawing specification.

Step 6 — Surface Treatment

Black oxide, zinc plating, phosphating, or hard chrome applied per customer specification.

Gear Hobbing Machine

Gear Milling Machine

CNC Gear Grinding Machine

Gantry CNC Machining Centre

Internal Grinding Machine

Planer Grinding and Turning

Precision Measurement Equipment

ISO 9001:2015 and Quality Certificates

Precision Measurement Equipment

ISO 9001:2015 Certification

Spur Gears

Standard spur pinions matching curved rack module for arc-path drives.

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Helical Gears

Helical pinions for quieter, higher-speed curved arc rack drives.

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Bevel Gears

Right-angle drive stages for curved rack systems where inline motor mounting is not possible.

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Planetary Gear Sets

Compact in-line servo reducers connecting motor to curved rack pinion shaft.

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Ring Gears

Large-diameter ring gears for full-rotation drives where a curved rack arc segment is used for partial travel.

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Plastic Gears

Nylon and POM pinions for quiet, lubrication-free light-duty curved rack drives in medical and food applications.

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Spur Gears

Pinion gears matching our spur gear rack range; standard modules m0.5 to m20.

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Ring Gears

Large-diameter internal or external ring gears for rotary and slewing drives.

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Bevel Gears

Straight and spiral bevel gears for right-angle drives and gear motor input stages.

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Helical Gears

Helical pinions for high-speed, low-noise rack drives and reduction stages.

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Planetary Gear Sets

Compact in-line reducers paired to servo motors; output shaft connects to the rack pinion.

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Worm Gear Wheels

Self-locking worm reducers for vertical rack axes holding position under gravity load.

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Plastic Gears

Nylon, POM, and polycarbonate pinion gears for light-duty, lubrication-free rack drives.

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How quickly will you reply to an enquiry?

We respond to most enquiries within 12 hours of receipt. For urgent requirements, contact our sales team directly by phone or email; we make every effort to provide a feasibility response and indicative price within the same business day, excluding national holidays.

Are curved rack and pinion sets made to order or held in stock?

Curved racks are made to order — the arc radius, subtended angle, module, and material are all specific to each application. We maintain a large stock of raw material, semi-finished blanks, and cutting tools so that production lead times are minimised. When you enquire, please provide the arc radius, arc angle, module, face width, material, and precision grade; we will return a lead-time with the quotation.

What should I provide to get an accurate price for a curved rack?

The most reliable way is to send a drawing in DXF, DWG, STEP, or PDF format specifying the arc radius, subtended angle, module, face width, precision grade, material, surface treatment, and mounting hole pattern. If no drawing is available, send the damaged part or a description of the required motion (input pinion size, total angular travel, drive force) and our engineering team will propose suitable parameters. We also reverse-engineer from sample parts.

Can curved racks be made in materials other than steel?

Yes. We produce curved racks in stainless steel (304, 316), brass, copper, aluminium 6061, POM acetal, and nylon PA66 in addition to standard C45 and alloy steels. Material choice depends on load, environment, and lubrication conditions. For food-processing and medical applications, 316 stainless or food-grade POM are most common. For robotics and semiconductor equipment, 304 stainless or aluminium with anodized finish are typical. Send us your application requirements and we will advise on the most cost-effective material for your duty cycle.

What is the minimum order quantity?

Minimum order requirements depend on the specific part — module, material, and arc geometry all affect whether we can economically run a small quantity. Send us your drawing or specification and we will state the minimum alongside the unit price and lead time. In general, for prototype quantities of one to five pieces, we are able to accommodate requests, particularly for robotics and medical equipment development programmes.

Can you manufacture metric curved racks to any module?

Yes. We have the tooling to manufacture curved racks in any metric module. Standard series M1 through M12 are our most common, but non-standard modules are available for OEM programmes where the module is fixed by an existing pinion in the customer system. Inch diametral pitch (DP) racks are also available; specify the DP and pressure angle alongside the arc geometry in your enquiry.

Are you a manufacturer or a trading company?

Ever-Power is a manufacturer. We operate our own production facility with CNC rack milling machines, gear hobbers, gear grinders, CMM inspection equipment, and heat treatment capability. We do not re-sell third-party products. All curved rack and pinion sets are produced, inspected, and documented in-house before dispatch.