Korea Ever-Power · NMRV Series · Barrier Gate and Security Gate Drive Guide

The boom barrier rotates a counterbalanced arm from horizontal (closed) to vertical (open) through approximately 90 degrees. The counterbalance spring reduces the motor torque required to lift the arm — the spring does most of the lifting work, and the motor primarily controls the speed and acceleration. The worm gearmotor output shaft is connected to the arm pivot, and the arm rotates in 2 to 6 seconds depending on the application. Fast-acting barriers for high-traffic carparks: 1.5 to 2.5 s open time. Security barriers: 3 to 6 s open time with obstacle detection.

Industrial security gates slide horizontally along a rail or cantilever from one side of the gate opening. Gate widths from 2 m to 12 m with leaf weights from 50 to 2,000 kg. The worm gearmotor drives a rack-and-pinion or chain drive mechanism that moves the gate leaf along the rail. Opening time typically 10 to 30 seconds. Self-locking prevents the gate from being pushed open manually when the motor is off.

Industrial swing gates (single or double leaf) rotate about a vertical hinge post through 90 to 120 degrees. The worm gearmotor is mounted at the hinge point and rotates the gate leaf about the hinge axis. Gate leaf weights from 50 to 500 kg. Opening time 10 to 30 seconds for industrial access gates. Self-locking holds the gate closed in wind gusts and prevents manual forcing when de-energised.

Security bollards rise from below ground level to above vehicle clearance height (typically 600 to 900 mm above grade) to block vehicle access. The worm gearmotor drives a vertical lifting mechanism through a 60:1 to 80:1 ratio providing high lift force from a small motor. Rising time 3 to 5 seconds. The very high self-locking torque at these ratios prevents the bollard from being pushed down by vehicle contact when the motor is off.

Forward drive efficiency: 72%
Back-drive efficiency: negative (self-locking)
Motor rated torque: 2.0 N·m (0.37 kW, 4-pole)
Output torque forward: 2.0 × 40 × 0.72 = 57.6 N·m
Force on boom arm at 300 mm radius: 192 N

Back-drive resistance: theoretically infinite — arm cannot be pushed down manually against the locked worm mesh.

A helical gearbox (efficiency 95 to 97%) does NOT self-lock — the gate can be pushed open manually when the motor is off because the helical gear mesh can be back-driven. To use a helical gearbox for a security gate, a separate electric brake or a mechanical lock solenoid is required to hold the gate closed. The NMRV worm gearmotor provides self-locking as an inherent mechanical property at ratios above 30:1, eliminating the cost and complexity of a separate locking mechanism. For barrier gate and security gate applications requiring intrinsic mechanical security, the NMRV worm gearmotor is the correct choice over the higher-efficiency helical gearbox.

Shopping centre and workplace carpark barriers may perform 500 to 2,000 operations per day. Each operation is 2 to 3 seconds open plus 2 to 3 seconds close. At 2,000 ops/day: 4,000 s motor-on time per day from an 86,400 s day = 4.6% CDF. This is S3 5% duty. The NMRV worm gearmotor thermal rating at S3 5% allows a significantly smaller motor than S1 continuous for the same peak torque output.

Port and airport security barriers: 50 to 200 ops/day. 4 to 6 second open and close. At 200 ops/day × 10 s/op: 2,000 s/day = 2.3% CDF = S3 5%. However, security barriers may have high-force impact resistance requirement: specify gearbox for 3× normal torque overload capacity for vehicle impact protection.

Factory perimeter gates and loading dock security gates: 10 to 50 ops/day. 15 to 30 second open and close for large sliding gates. Very low CDF (below 1%). NMRV gearmotor thermal rating is never challenged at this cycle rate. Motor selection driven by peak torque to move gate leaf, not thermal duty.

Barrier gate and security gate gearmotors are almost always installed outdoors, exposed to rain, wind-driven water, and periodic hosing or pressure washing of the gate cabinet and surrounding area. IP55 (dust-tight, protection against water jets) is the minimum enclosure rating for outdoor gate motors. The Y2 and YS motors in the NMRV gearmotor combination are rated IP54 standard; specify IP55 upgrade for outdoor gate installations. The NMRV gearbox itself must also be sealed to IP55 with synthetic gear oil fill for outdoor service.

Outdoor gate motors in cold climates may need to start against a frozen or ice-laden gate leaf at ambient temperatures below -15°C. Three concerns at low temperature: standard NMRV mineral oil thickens dramatically below -15°C, increasing the viscous drag on the worm mesh and requiring more starting torque; motor starting torque is slightly reduced at low temperature; and counterbalance springs become stiffer and may not offset arm weight as effectively as at rated temperature. Specify synthetic PAO gear oil in the NMRV for cold climate service, and verify that the motor locked-rotor torque at the minimum operating temperature is sufficient to overcome the increased viscous drag plus the unbalanced gate load.

The Korea Ever-Power NMRV gearmotor is the compact right-angle worm gearmotor solution for boom barriers, security gates, sliding gates, and rising bollard drives requiring self-locking, high output torque, low output speed, and outdoor IP55 protection. NMRV 030 to 063 sizes with YS small-power or Y2 standard motors from 0.06 to 1.1 kW cover all boom barrier and medium-duty sliding gate applications. The complete NMRV gearmotor range is in the gearmotor product section. For high-security bollard and heavy industrial gate specifications above 1.5 kW, contact Korea Ever-Power for custom configuration.

Security bollards rising 600 to 900 mm in 3 to 5 seconds. NMRV 040 or 050 at 60:1 to 80:1, YS 0.12 to 0.37 kW. Very high self-locking torque holds bollard against vehicle impact when de-energised. IP55 essential — below-grade installation exposed to water ingress. Stainless fasteners for corrosion resistance in wet pit.

Airside perimeter security barriers with high-security forced entry resistance. NMRV 063 at 60:1 to 80:1, Y2 0.37 to 0.75 kW. 4 to 6 second arm travel. Obstacle detection safety edge mandatory. Motor sized for 2× normal torque to handle safety reversal from closed against an obstacle. Self-locking prevents airside unauthorised passage when motor is off.

Heavy vehicle blockers at government facilities, embassies, and critical infrastructure sites. Very high rated impact resistance (K12, K4 rating). NMRV 090 at 60:1 to 80:1, Y2 1.5 to 4.0 kW. Raise time 3 to 5 s. The NMRV self-locking torque combined with the mechanical blocker structure provides the rated vehicle impact resistance when the blocker is deployed.

Residential estate and commercial property swing gates from 2 to 5 m per leaf, 50 to 300 kg. NMRV 030 or 040 at 30:1 to 60:1, YS 0.06 to 0.25 kW. 10 to 20 second open time. Low cycle (20 to 100 ops/day). Self-locking holds gate against wind loading and prevents casual manual forcing without actuator.