K Series Bevel-Helical Gear Reducer

Right-angle bevel-helical gear reducer combining a hardened spiral bevel first stage with one or two helical reduction stages, available in sizes K37 through K187. Provides the 90° shaft direction change of a worm gearbox with the higher efficiency and higher output torque capacity of helical gearing. The preferred specification for heavy-duty right-angle drives including large conveyor tail-end drives, material handling crane drives, and process industry agitator drives where both right-angle geometry and high efficiency are required simultaneously.

Sizes: K37 – K187
Ratios: 5.36 – 197.37
Output Torque: 200 – 50,000 N·m
Right-Angle 90° Output
Efficiency: up to 97%
IP55 Protection

Kategória: Worm Gear Reducers

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90° Bevel-Helical

Up to 97% Efficiency

IEC B5 Motor Flange

Hollow Shaft Option

50,000 N·m Peak Torque

ISO 9001 Certified

K Series Bevel-Helical Gear Reducer Korea Ever-Power

K Series Bevel Helical CNC Precision Machining

Right-Angle Drive with Helical Efficiency: The Bevel-Helical Advantage

The K series combines two distinct gear types in a single gearbox body. The first stage is a hardened spiral bevel gear pair that changes the shaft direction by 90° — the same function as a worm first stage, but at efficiency of 97 to 98% versus the 48 to 60% typical of a worm first stage at ratios of 5:1 to 10:1. The subsequent helical stages provide further ratio reduction at up to 98% per stage, giving the K series a typical overall efficiency of 93 to 97% depending on the number of stages and total ratio, compared to 48 to 58% for a worm gearbox at the same ratio.

The spiral bevel first stage uses lapped bevel gear pairs with a spiral tooth form that distributes contact load along a curved tooth face line rather than concentrating it at a point, producing significantly lower noise and vibration than a straight-cut bevel gear pair while achieving the same 90° shaft direction change. Bevel gear materials are 20CrMnTi case-hardened alloy steel, lapped in matched pairs, so the drive and pinion from each matching pair must be used together and should not be interchanged between units.

The output torque range of the K series (200 N·m to 50,000 N·m) significantly exceeds what is available from worm gearboxes in the same shaft-centre-distance footprint, making the K series the only practical right-angle option for drives above approximately 1,500 N·m output torque where worm gearbox size and weight become excessive.

Explore matched motors at Three-Phase Induction Motors, or browse all gearbox types at Helical Gear Reducers.

K Series Size and Performance Data

Performance data at rated input speed 1440 rpm (4-pole motor). 2-stage and 3-stage bevel-helical configurations available per size.

Size	Stages	Ratio Range	Max Output Torque (N·m)	Efficiency (%)	IEC Motor Frames	Max Input kW	Weight (kg)
K37	2	5.36 – 34.86	200	95	80, 90, 100	2.2	9
K47	2 / 3	5.36 – 197.37	350	93 – 95	90, 100, 112	4.0	14
K57	2 / 3	5.36 – 197.37	550	93 – 95	100, 112, 132	7.5	22
K67	2 / 3	5.36 – 197.37	900	93 – 95	112, 132, 160	11	34
K77	2 / 3	5.36 – 197.37	1,500	93 – 95	132, 160, 180	18.5	55
K87	2 / 3	5.36 – 197.37	2,500	93 – 95	160, 180, 200	30	82
K97	2 / 3	5.36 – 197.37	4,000	93 – 95	180, 200, 225	55	118
K107	2 / 3	5.36 – 197.37	6,500	93 – 95	200, 225, 250	75	172
K127	2 / 3	5.36 – 197.37	10,000	93 – 95	225, 250, 280	110	265
K157	2 / 3	5.36 – 197.37	20,000	93 – 97	250, 280, 315	160	420
K187	2 / 3	5.36 – 197.37	50,000	93 – 97	280, 315	250	720

Gearbox Specifications

Bevel gear material	20CrMnTi case-hardened
Helical gear material	20CrMnTi case-hardened
Bevel tooth form	Spiral (Gleason)
Housing material	GJL-250 cast iron
Gear oil	ISO VG 220 synthetic
Protection	IP55
Shaft angle	90° (standard)
Mounting	Any orientation

Input and Output Options

Input type	IEC B5 flange direct
Output shaft	Solid keyed (standard)
Hollow shaft	Shrink disc (K47 up)
Output flange	Available K47 and above
Shaft positions	Multiple B, C, D, E
Torque arm	Included with hollow shaft
IEC frame range	80 – 315
Standards	ISO 9001 / CE

Typical Applications for K Series Bevel-Helical Reducers

K Series Bevel Helical Reducer Mining Conveyor Application

Heavy Conveyor Tail-End Drives

Underground mine conveyors and tunnel conveyor tail-end drives use K series reducers where the motor must be oriented at 90° to the conveyor belt to fit within the tunnel cross-section. The K series delivers the right-angle geometry without the efficiency penalty of a worm drive at the high output torques (above 2,000 N·m) required for heavy loaded belt drives.

K Series Bevel Helical Reducer Industrial Agitator Application

Side-Entry Tank Agitators

Large-diameter side-entry agitators on crude oil storage tanks and chemical process vessels use K series reducers for their right-angle geometry (motor on top, agitator shaft horizontal), high output torque capacity exceeding 10,000 N·m, and substantially lower heat generation than worm alternatives at the same power level.

K Series Bevel Helical Reducer Material Handling Application

Crane and Hoist Drives

Overhead crane long-travel and cross-travel drives use K series bevel-helical reducers to orient the motor perpendicular to the runway rail while driving the wheel axle shaft, producing the compact right-angle package needed to fit within the crane bridge girder end-carriage envelope.

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Extruder Main Drives

Rubber and plastic extruder main gearboxes use K series bevel-helical reducers where the motor must be positioned above or beside the extruder barrel rather than behind it, minimising the floor length of the extruder line. The high output torque of K187 (50,000 N·m) covers large twin-screw extruder applications that worm gearboxes cannot approach.

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Bucket Elevator Drives

Bucket elevator head shaft drives use K series reducers to position the motor on the side of the elevator casing rather than above the head pulley, reducing the total installation height of the elevator in buildings with limited headroom clearance above the elevator discharge point.

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Kiln and Dryer Drives

Rotary kiln and rotary dryer main drives require a 90° right-angle from the main reduction gearbox to the pinion gear on the kiln shell. K series reducers provide this right-angle with the high torque capacity and long service life demanded by continuous 24-hour cement and mineral processing kiln operation.

K Series vs Worm Gearbox for Heavy Right-Angle Drives

Efficiency at High Power

At output torques above 1,500 N·m, the efficiency advantage of the K series over the worm gearbox becomes economically decisive. A 55 kW right-angle drive at 50:1 ratio: worm gearbox efficiency approximately 52%, so 26 kW dissipated as heat in the gearbox housing. K series efficiency approximately 93%, so only 3.9 kW dissipated. The worm gearbox at this power level requires a forced oil cooler and may exceed safe housing temperature limits without additional cooling. The K series requires no cooling beyond natural convection, simplifying the installation and eliminating the cooling system as a potential failure point.

Output Torque Ceiling

The largest standard worm gearbox (NMRV150) has a maximum output torque of approximately 1,500 N·m. Above this level, worm gearbox solutions require purpose-built or very large housing designs that are heavy, expensive, and slow to procure. The K series provides standard off-the-shelf output torques from 1,500 N·m (K77) through 50,000 N·m (K187), covering the heavy right-angle drive range from conveyor head pulley drives through extruder main gearboxes from a single standard product family.

Back-Driveability and Load Holding

The K series is back-driveable at all ratios, unlike the worm gearbox which self-locks above 30:1. For heavy inclined conveyor drives and crane drives, this means a separate electromagnetic brake motor is required with the K series for load holding when the motor stops — the same requirement as the R and F series helical gearboxes. For applications where the worm self-locking characteristic was the deciding factor (gate drives, goods lifts), the S series helical-worm gearbox provides an intermediate option with higher efficiency than a pure worm gearbox while retaining the right-angle geometry and self-locking at high ratios.

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Engineering Team

QC Inspection

CE and ISO Certifications

Frequently Asked Questions — K Series Bevel-Helical Reducer

Can the K series output shaft be oriented in multiple directions?

Yes. The K series gearbox body is available in multiple output shaft position codes (B, C, D, E) that determine the angular position of the output shaft face relative to the motor input flange. This allows the output shaft to point in any of four 90° positions relative to the motor, giving maximum flexibility in fitting the motor-gearbox assembly into the available installation envelope. The output shaft is always at 90° to the motor input shaft regardless of the position code; the position code only determines which face of the gearbox the output shaft exits from. Korea Ever-Power provides position code drawings in the product catalogue for each K series size.

Why must bevel gear pairs be kept as matched sets?

Spiral bevel gears are lapped together in matched pairs at the factory. Lapping grinds the two gear surfaces together until the contact pattern across the tooth face meets the required specification. The contact pattern of a lapped pair is unique to that combination of drive and pinion: mixing a drive gear from one pair with a pinion from a different pair, even of the same nominal size and ratio, will produce an incorrect contact pattern, elevated noise, and accelerated wear. Each K series gearbox is therefore shipped with the matched bevel pair installed as a set, and the pair identification number is stamped on both components. Spare bevel pairs for maintenance are always supplied as matched sets with matching identification numbers.

What is the recommended oil type and change interval for K series?

The K series is supplied filled with synthetic ISO VG 220 gear oil as standard. The first oil change is due at 500 operating hours to flush running-in debris. Thereafter, synthetic oil change intervals of 10,000 hours (or 5 years, whichever comes first) apply in normal operating conditions below 80 °C oil temperature. The bevel gear stage requires an oil grade with hypoid gear additives (GL-5 specification) because the spiral bevel tooth contact includes a sliding component under high contact stress. Standard ISO VG 220 industrial gear oil may not contain sufficient extreme pressure additives for the bevel stage; Korea Ever-Power recommends a synthetic ISO VG 220 oil with GL-5 rating for K series applications.

What is the axial force generated by the K series bevel stage?

Spiral bevel gears generate axial (thrust) forces in addition to the radial forces from gear tooth load. The magnitude and direction of the axial force depend on the helix hand of the spiral and the rotation direction. In the K series, the bevel stage axial forces are absorbed by angular contact ball bearings or taper roller bearings at the bevel pinion shaft, and these bearings are sized to handle the axial component of the rated torque load. The axial force is internal to the gearbox and does not appear at the motor or output shaft as an external force, so the K series imposes no additional axial load on the motor bearings or the driven equipment bearings beyond what is normal for a helical output stage.

Is the K series suitable for frequent start-stop duty at high inertia loads?

The K series is rated for start-stop duty with a standard service factor applied to the output torque rating. For applications with frequent starts (above 10 per hour) at high inertia loads (heavy flywheels, large agitator impellers), the dynamic torque during acceleration can significantly exceed the steady-state running torque. Korea Ever-Power recommends applying a service factor of 1.75 to 2.0 for heavy shock start-stop duty, meaning the gearbox torque rating must exceed 1.75 to 2.0 times the running torque requirement. For applications exceeding 30 starts per hour or requiring starting under full locked-rotor torque, a detailed service factor calculation should be submitted to Korea Ever-Power for confirmation of the appropriate gearbox size before ordering.

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Edited by Cxm

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Editor	Cxm