EP-AP / EP-APK Series Curvic Plate Rack-Drive Planetary Gearbox

The EP-AP series Curvic Plate rack-drive planetary gearbox is the Korea Ever-Power product engineered specifically for large-format rack-and-pinion linear drive systems — gantry machine tools, large laser cutters, panel handling systems, and heavy portal cranes where the gearbox drives a rack-mounted pinion that traverses a linear axis. The Curvic Plate's self-centring single-screw design solves the most operationally demanding maintenance requirement of rack-and-pinion systems: rapid, repeatable pinion replacement when the pinion tooth flank wears, without removing the gearbox or disturbing the servo motor cable connections.

Four variants cover the installation geometry range: AP inline and APC compact inline for coaxial motor-to-pinion layouts, and APK right-angle and APCK compact right-angle for machines where the servo motor must be positioned perpendicular to the rack axis. All variants share the same Curvic Plate output interface, the same 090–450 mm frame size range, the same ≤1 to 2 arcmin backlash specification, and the same 315–14,010 N·m output torque range.

Three Engineering Advantages the Curvic Plate Delivers

EP-AP — Inline Standard

Standard inline configuration — motor and Curvic Plate output share a common axis. Used in Korean gantry machine tools and large laser cutting systems where the servo motor is coaxial with the rack drive axis. Backlash ≤1 to 2 arcmin (1–3 stage configurations).

EP-APC — Compact Inline

Compact housing version of AP — same inline geometry and Curvic Plate interface, reduced gearbox body length. Used when the carriage assembly depth is constrained and the motor-to-rack dimension must be minimised. Same backlash and torque specification as AP.

EP-APK — Right-Angle

Right-angle output — servo motor perpendicular to the rack axis. Used in Korean heavy portal cranes, panel handling systems, and large gantry structures where the servo motor cannot be positioned coaxially with the rack due to structural clearance. Backlash ≤2 arcmin (2–4 stage configurations).

EP-APCK — Compact Right-Angle

Compact housing right-angle variant — combines the perpendicular motor layout of APK with a reduced gearbox body for space-constrained carriage designs. Same Curvic Plate interface and ≤2 arcmin backlash as APK.

Gantry Machine Tools — AP on Both X-Axis Sides

Korean large-format gantry machining centres — 5-axis gantry mills for aerospace structural parts, large mould machining centres, bridge-type machining centres — use EP-AP on the X-axis rack drive on both sides of the gantry bridge. Gantry synchronisation requires the same pinion-to-rack mesh geometry on both sides after every maintenance event. Curvic Plate's self-centring guarantees that both sides restore to the same mesh position after pinion replacement, maintaining gantry synchronisation accuracy without a re-calibration run across the full X-axis travel. AP200–AP285 cover the torque range of Korean aerospace and mould-making gantry machine tool X-axis drives. For offset motor mounting configurations, pairs with precision CV drive shafts for dual-drive carriage synchronisation.

Large-Format Laser Cutting Systems — APC Compact

Korean large-format fibre laser cutting systems for steel plate and structural section cutting — 4 m × 20 m working area, cutting heads travelling at 60–150 m/min — require rack-drive gearboxes on the long-axis carriage that minimise the carriage profile depth while delivering the torque needed for high-speed acceleration. EP-APC compact inline Curvic Plate reduces carriage depth compared to standard AP while maintaining the single-screw pinion replacement capability. At Korean laser cutting production rates (multiple shifts, high feed rates), pinion wear intervals are measured in months rather than years; the Curvic Plate replaces a multi-hour downtime maintenance event with a 30-minute procedure that does not interrupt the production shift.

Heavy Portal Cranes — APK Right-Angle for High Rack Force

Korean shipyard and heavy industry portal cranes traversing on rack-and-pinion rail systems — handling loads up to 500 tonnes over 100 m travel distances — require rack drive gearboxes at the upper range of EP-AP: APK200 to APK450, right-angle configuration with the drive motor positioned across the crane bridge perpendicular to the travel direction. At 14,010 N·m maximum output, APK450 addresses the highest crane rack drive torque in the Korea Ever-Power range. The −10 °C lower temperature limit covers outdoor Korean winter crane operation.

Automated Panel Handling — APCK Compact Right-Angle

Korean flat-panel display and semiconductor substrate automated material handling systems — large panel transport carriages, glass substrate handling gantries — use EP-APCK compact right-angle on the linear drive axes. The compact housing reduces carriage height for under-gantry clearance requirements, the right-angle layout places the motor within the carriage structure perpendicular to the travel axis, and the Curvic Plate provides the rapid pinion replacement capability needed in cleanroom-adjacent maintenance environments where extended on-machine work is restricted.

Plasma and Waterjet Cutting Gantries — AP for Heavy Plate

Korean heavy plate cutting operations — plasma cutting of 100 mm structural steel, waterjet cutting of composite structures — use rack-driven gantry systems with EP-AP for the long-axis drive. Heavy plate cutting imposes high cutting reaction forces on the rack drive; AP's torque capacity up to 14,010 N·m absorbs these forces while the Curvic Plate's single-screw pinion allows maintenance on the shop floor without specialist tooling. AP140 and AP200 cover the torque range of Korean standard plasma and waterjet heavy-plate gantry drives.

Renewable Energy Manufacturing — Long-Axis Gantry Drives

Korean wind turbine blade manufacturing gantries and large solar panel frame fabrication systems use rack-driven long axes up to 50 m travel. EP-AP on these systems benefits from the Curvic Plate maintenance capability, since gantry systems in production environments run at multi-shift utilisation rates that accelerate pinion wear cycles. Downstream integration with agricultural bevel gearboxes is not typical for this application class, but gravity-hold braking via worm gear reducers is used on vertical gantry axes where rack-driven Z-columns must hold position on power-off.

• ✔Curvic Plate face-gear geometry verified — self-centring accuracy confirmed per batch
• ✔Backlash ≤1–2 arcmin (AP/APC) and ≤2 arcmin (APK/APCK) measured at output per unit
• ✔Full-load torque test — critical at AP355 and AP450 high-torque frames
• ✔IP65 ingress test per IEC 60529 — every unit
• ✔Material certificate and dimensional drawing with every delivery

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EP-AP200 on a 12 m × 5 m gantry machining centre — both X-axis sides. Previous gearbox used a splined pinion: our first pinion change on each side took 3.5 hours including gantry re-synchronisation after each side, machine downtime 7 hours total. With AP Curvic Plate both sides were done in 55 minutes, no gantry re-synchronisation required — the Curvic Plate restored both sides to within 0.008 mm of pre-change gantry sync without a calibration run. At our planned maintenance interval, this is a 7-hour to 55-minute improvement, twice per year per machine. On 6 machines over 2 years, we have accumulated over 70 hours of recovered production time from this single change.

EP-APC140 compact inline on a 6 m × 20 m fibre laser cutting system — 120 m/min max feed rate, three-shift operation. Previous standard gearbox pinion life was 4–5 months at this utilisation; replacement was scheduled as a half-day event requiring a service engineer. APC Curvic Plate made pinion change a first-shift maintenance task: operator loosens one screw, swaps pinion, tightens one screw — confirmed cutting accuracy within one test cut. We have now completed 9 pinion replacements across 4 machines with no laser positional accuracy recertification required after any replacement. Korea Ever-Power application team calculated the correct pinion module for our rack specification before we finalised the APC frame size.

EP-APK355 right-angle for a shipyard portal crane traversal rack drive — 380-tonne crane, outdoor operation, motor mounted horizontally across the bridge. Required 9,200 N·m at the output. The Korea Ever-Power team specified APK355 from our rack force and travel speed data. Three winters of outdoor operation to −6 °C without lubrication issues. First pinion replacement at 18 months: dock foreman reported the replacement was completed by the in-house maintenance crew in 40 minutes — the previous spline-type gearbox pinion on an older crane in the same yard takes a full day with contracted maintenance. The crane was back in operation the same shift. We are now replacing all four rack drive gearboxes on that crane with APK at next scheduled maintenance.

CV Joint Drive Shafts

For dual-drive gantry configurations where two EP-AP units drive the same rack from both sides of the gantry bridge — common on large Korean machining centres and portal cranes for synchronised bilateral drive — precision heavy-duty CV joint drive shafts connect the second drive unit's output to the carriage structure through an angular offset, maintaining synchronisation torque transfer without introducing additional backlash.

Worm Gear Reducers

For vertical rack-driven Z-columns on Korean gantry machining centres and crane bridge elevation drives — where the rack-driven vertical axis must hold position under gravity load on servo power-off — self-locking worm gear reducers downstream of the EP-AP vertical axis gearbox provide gravity load holding without electromagnetic brakes, supplementing the AP Curvic Plate gearbox with position holding at any vertical position.

Agricultural Gearboxes

EP-AP/APK is a large-frame high-torque series not typical of agricultural machinery rack drives. For Korean large-scale precision agricultural gantry seeding and spraying systems with rack-driven long-axis traverse, where EP-AP provides the primary rack drive reduction and downstream agricultural bevel gearboxes distribute spray or seed output along the boom width, Korea Ever-Power supplies the agricultural bevel stages rated for the AP output torque at the distribution point.

QWhat is a Curvic Plate and why does it matter for my rack-and-pinion system?

A Curvic Plate is a curved-tooth face-gear disc that connects the output pinion to the EP-AP gearbox output shaft via a single clamping screw. The curved tooth geometry self-centres the pinion on the gearbox shaft — when the screw is tightened, the Curvic teeth force the pinion to the same centreline position every time, regardless of the installation sequence. For a rack-and-pinion system, this matters because the pinion is a wear component that must be replaced periodically. With a Curvic Plate, pinion replacement is a one-screw operation that takes 15–30 minutes and requires no realignment. With a conventional spline or key connection, pinion replacement requires removing the gearbox, extracting the pinion with specialised tools, and realigning the gearbox after reinstallation — typically 2–4 hours including machine recalibration.

QCan I use EP-AP for a rotary (non-rack) application that requires 10,000+ N·m?

Technically, EP-AP provides output torque for any connected load — the Curvic Plate is the output interface but the torque capacity is the gearbox's property. However, the Curvic Plate output interface is optimised for rack-and-pinion pinion connection, not for rotary table flanges or solid shaft couplings used in typical rotary drive applications. For a rotary application at 10,000+ N·m where rack-drive pinion connection is not required, the New Line EP-AH series (up to 9,585 N·m) may cover the requirement; for torques above 9,585 N·m in a rotary configuration, contact Korea Ever-Power to discuss whether EP-AP in a rotary configuration is technically feasible and whether the output interface geometry suits the load connection.

QMy rack-and-pinion system uses a 90-degree motor layout. Is APK or APCK the right choice?

Both APK and APCK provide a 90-degree right-angle output with the same Curvic Plate interface. The choice is based on carriage depth constraint: if the available depth for the gearbox body (measured from the rack centreline rearward into the carriage structure) meets the standard APK housing dimensions, specify APK. If the carriage depth is constrained and a shorter gearbox body is required, specify APCK. Both carry the same ≤2 arcmin backlash specification and the same Curvic Plate single-screw pinion interface. Contact Korea Ever-Power with your carriage envelope dimensions and the team will confirm which variant fits.

QHow do I calculate the required EP-AP frame size from my rack-drive specification?

The required gearbox output torque for a rack-and-pinion drive is: T (N·m) = F × r, where F is the tangential rack force (N) and r is the pinion pitch circle radius (m). The tangential rack force combines the cutting force (or handling load) and the acceleration force from the moving mass. Korea Ever-Power provides a rack drive torque calculation worksheet in Korean — supply your rack module, pinion tooth count, moving mass, maximum acceleration rate, and maximum cutting or handling force, and the application team returns the required output torque and the recommended AP frame size. This calculation is provided as a standard pre-order service for EP-AP/APK.

QDoes the AP/APK backlash (≤1–2 arcmin) affect linear positioning accuracy on the rack axis?

Yes — gearbox backlash translates directly to angular uncertainty at the pinion, which then translates to a linear position uncertainty on the rack axis. The linear equivalent of ≤1 arcmin at the pinion is: Δx = r × (1 arcmin in radians) = r × 0.000291 radians, where r is the pinion pitch circle radius. For a typical 25 mm pitch radius pinion, ≤1 arcmin corresponds to ≤0.0073 mm linear uncertainty. For Korean machine tool applications where the rack axis linear accuracy is specified to ±0.01 mm or better, the AP/APC ≤1–2 arcmin inline backlash is within the budget. For the right-angle APK/APCK at ≤2 arcmin, the same calculation applies. If the accuracy specification is tighter than the gearbox backlash budget allows, a closed-loop linear scale feedback on the rack axis compensates the gearbox backlash contribution.