Brand: Flender

Flender ARPEX AKR Safety Coupling Torque Limiter

Name: Flender ARPEX AKR Safety Coupling – Datasheet & Quote
Brand: Flender
SKU: ARPEX AKR

Description

An ARPEX torque limiter that disconnects the drive on overload

The Flender ARPEX AKR is an ARPEX safety coupling (torque limiter) from catalog FLE 10.7, edition 2026. Flender says ARPEX torque limiters are used wherever modern, high-grade machines need reliable protection in case of overload, avoiding long standstill periods and repairs. They are available in fourteen sizes for torques from 13 Nm to 65,000 Nm, with higher disconnecting torques on request.

Two designs are offered: the standard design AKR for combinations with standard ARPEX and N-EUPEX components, and the shaft mounting design AKA for belt-pulleys or chain wheels. This page concerns the AKR.

Technical specifications

Parameter	Specification
Series	AKR (standard design), AKA (shaft mounting design); catalog FLE 10.7 Edition 2026
Size 02	Disconnecting torque 60 to 200 Nm; n max 5,000 rpm; max bore 35 mm; 3.5 kg
Size 06	550 to 1,500 Nm; 2,800 rpm; max bore 65 mm; 16.6 kg
Size 08	1,800 to 3,500 Nm; 2,600 rpm; max bore 80 mm; 29.7 kg
Size 10	3,600 to 10,000 Nm; 1,700 rpm; max bore 110 mm; 73.4 kg
Size 11	9,000 to 25,000 Nm; 2,200 rpm (1,450 rpm with clamping sleeve); max bore 160 mm; 165 kg
Size 13	29,000 to 65,000 Nm; 1,800 rpm (1,100 rpm with clamping sleeve); max bore 220 mm; 324 kg
Bore / keyway	Bore and keyway to DIN 6885-1, or with clamping sleeve; flanged component bore fit N7
Disconnecting torque	Adjusted at the factory to the customer specification: TA = 1.2 x Tmax
Maximum temperature	Refrain from heating above +80 C (bearing life)
Document	Flender safety couplings catalog FLE 10.7, Edition 2026 (40 pages)

How it works

The torque limiter transmits torque over a disc pack to indexing rings engaged by close-fitting splines held in place by plate springs. On overload the indexing rings turn against each other and push the splines out of engagement. The plate springs then jump into a negative position, the splines are out of gear and the coupling halves have no contact, so they are wear-free after disengagement and the unit does not re-engage by itself. The axial movement of the indexing ring can actuate a limit switch that stops the machine. Re-engagement is possible only when the plant is stationary, guided by fixed point markings offset at 120 degrees.

Selection and ordering

The disconnecting torque should be at least 120 percent of the maximum torque in the plant, TA = 1.2 x Tmax, including start-up peaks. Torque limiters are delivered ready for assembly with the torque set as specified; additional ARPEX, N-EUPEX or RUPEX parts are supplied unassembled. State the disconnecting torque, bore, keyway, speed and the combined coupling. Coupling items are grouped in Electric Motors; a related published product is the Flender ONE gear unit.

How the Flender ARPEX AKR torque limiter protects a drive

A torque limiter is a safety link between a driving and a driven machine. In normal running it transmits the torque through a disc pack to indexing rings that are held in mesh by close-fitting splines. The torque at which it disconnects is set at the factory to the customer specification, as 1.2 times the maximum torque of the drive. If a jam or blockage makes the torque exceed that value, the indexing rings turn against each other and push the splines out of gear. The plate springs then snap into a negative position and the two coupling halves are no longer in contact, so there is no wear while the machine runs down. The coupling does not re-engage by itself.

Where the ARPEX AKR is used

Drives that may jam, such as crushers, conveyors and mixers.
Machines with high-value gearboxes or motors that need protection.
Plants that must avoid long standstills and costly repairs after an overload.
Drives that already use ARPEX or N-EUPEX components.

Selection checklist for the ARPEX AKR

Size, from 02 to 13 in the catalogue range, chosen from the disconnecting torque.
Disconnecting torque, from 60 Nm in size 02 up to 65,000 Nm in size 13.
Maximum speed for the size, and the lower limit with a clamping sleeve.
Maximum bore of the hub and the type of shaft connection: bore with keyway to DIN 6885-1, or clamping sleeve.
Standard design AKR, or the shaft mounting design AKA when a belt pulley or a chain wheel is used.
Limit switch on the axial movement of the indexing ring, to stop the machine.
Ambient temperature, which should stay below 80 degrees C for bearing life.
Weight and space in the drive train.

Installation, commissioning and maintenance notes

Fit the hubs on the shafts and align the machines as the catalogue states. Connect the limit switch to the machine control so that the drive stops when the coupling disengages. After a disengagement, find and remove the cause of the overload before the coupling is reset. Re-engagement is done only with the plant standing still, using the fixed points marked on the coupling. Check the coupling from time to time for wear and for the condition of the bearings.

Requesting a quotation for the Flender ARPEX AKR

Send the size, the disconnecting torque, the speed and the shaft diameters. Seven Star LLC serves industrial customers in Oman and the GCC and replies with a quotation based on the information provided.

Why the setting is made at the factory

The disconnecting torque is a safety value for the drive, so it is set in the factory to the stated specification. Give the maximum torque of the drive when you order.

Wear-free after disengagement

Because the halves have no contact after the splines leave the mesh, there is no friction while the machine coasts down, which keeps the parts in good condition.

Records for safety couplings

Keep the order data and the set torque with the machine records so that any replacement coupling is set the same way.

Documents and quotation

The Flender document is attached. Seven Star LLC supplies Flender couplings on request and quotes against the exact type, size and bore. The attached catalog contains the full dimension tables and combination options (AKR with ARPEX and N-EUPEX) for the AKR and AKA series.

Datasheets & Documents

Datasheet Flender catalog FLE 10.7 Edition 2026 Safety Couplings ARPEX (EN) Download

Reviews (0)

Reviews

There are no reviews yet.

How would you rate this product?

About brand

Large industrial gearboxes are the product most engineers associate with Flender, a company founded in 1899 and based in Bocholt, Germany, that builds gear units, couplings and drive systems. Seven Star LLC sources and supplies Flender gear units and their spare parts for mills, conveyors, pumps and marine drives in Oman, working from the nameplate data. On some nameplates the name appears as Siemens Flender.

Flender gearbox types listed here

Four items are listed. Flender ONE is the manufacturer's redesigned single-stage helical gear unit. The H2SV 09 is a two-stage helical gear unit of size 09 with a solid output shaft, shown here with a cooling coil and oil tank. The NAVILUS line covers marine gearboxes, listed in a multiple-input, single-output arrangement that brings several engines onto one propeller shaft, and in a version for dredgers. Flender couplings such as the flexible N-EUPEX type are often ordered with a gear unit.

Ordering a Flender gearbox or parts: what we need

Send a photo of the nameplate showing type, size, serial or order number, ratio, power and speeds. For spares, the serial number lets the parts list be traced, so add the item number of the bearing, seal or gear set you need. For a new unit, give the driven machine, motor power and speed, output speed, mounting position, shaft arrangement, ambient temperature and cooling method. Marine and dredger gearboxes for GCC yards also need the class society.

Browse Flender products by category: Electromotors, Electric Motors & Pumps.