Simplex stern tube and marine shaft seal services, shaft couplings, bearings and spare parts

The OK coupling has gained worldwide approval with more than 50,000 units being installed. It is very simple to install and dismantle using hydraulic pressure to achieve an interference fit, whereby two shafts can be joined, and high levels of torque and axial loads can be transferred without the requirement for keyways or taper / thrust rings, and without creating stress points or fretting in operation.  

To install the OK coupling, slide the thin inner sleeve onto the shaft.  This inner sleeve has a tapered outer diameter.  A thick outer sleeve with matching tapered inner surface is fitted onto the inner sleeve. Ordinary mineral oil is injected between the sleeves and a built-in jack drives the outer sleeve up the taper of the inner sleeve.  Once the outer sleeve reaches its final position, an interference fit is created by releasing the hydraulic pressure. Later the coupling can be easily removed by reversing the process.   

The range consists of:

• the OKC joins two cylindrical shafts  

• the OKF joins a cylindrical shaft to a shaft with a flange

• the OKCX has a special carbide friction coating, which allows a 50% greater torque capacity or a smaller, lighter unit. It joins two cylindrical shafts

• the OKFX has a special carbide friction coating, which allows a 50% greater torque capacity or a smaller, lighter unit. It joins a cylindrical shaft to a shaft with a flange

The range caters for shaft diameters from 45 mm to 1,000 mm and forces up to 23,630 kNm.  Tailor-made solutions are available as a “supergrip” bolts for rotating flanges.

Tough marine environments can play havoc on an aft seal’s effectiveness – dirt, fishing lines, and nets can all be responsible for mounting maintenance costs. SIMPLEX net protection solutions include three options, used individually or in combination, for protecting the aft seal from damage caused by fishing nets or lines.

• Simplex net protector ring is a dirt, net and rope protection ring that is fully split and is positioned in front of the first sealing ring
• Simplex net cutter has stainless steel blades fixed onto the rope guard or propeller
• Simplex net pick-up is a fully split ring mounted just inside the rope guard to collect any net, line or rope before it reaches the aft seal

Bulkhead seals

We have a special range of seals where there is a risk of flooding through bulkhead openings. These are fitted on a wide range of vessels, such as chemical and product tankers, gas tankers, offshore vessels, naval vessels etc. These can be used in gas-tight applications, as well as in explosion hazard areas.

Rudder stock seals

For simple applications we supply an easy to fit packing gland, but where the seal has to be located near to the waterline, we recommend the Simplex rudder stock seal, which is very similar to the sterntube seal and can be supplied with grease or oil lubrication.

Sterntube bearings

We supply white metal bearings, with backing material made in either GG-20 or GGG-40, for ships which are subject to higher stresses, such as icebeakers. The maximum length is 2,800 mm and the maximum diameter is 1,200 mm. The oil groove can be straight or helical for twin screw vessels.

We also supply the Simplex BlueRun polymer sterntube bearing for water lubricated applications, irrespective of whether they are closed or open systems. A split version is available for those where there is no need to pull the shaft in order to replace the bearing. The maximum shaft diameter is 500 mm.

Complete sterntubes

We supply sterntubes, complete with white metal bearings, with full piping ready to install. The forward mounting point of the sterntube has a sliding fit in order to compensate for any temperature differential between the water and the sterntube in order to avoid the risk of the ship’s hull suffering stress cracking. Alignment of the sterntube is made much easier by the use of epoxy resin, together with the patented sealing package for the resin.

Intermediate shaft bearings

The Simplex intermediate shaft bearings have been specifically designed for propulsion shaft applications with a short length, so they can be precisely aligned without risk of edge loading. The bearings are self-lubricating and the oil pocket design ensures optimised oil distribution, even at slow rotational speeds. The advanced white metal bearing material provides optimal performance, including emergency running.

The bearings are available as pedestal bearings or saddle bearings with sizes up to over one metre.

Sealed bearings are available to ensure continued operation, even if the shaft is flooded.

Thrust bearings

The Simplex high load thrust bearings are single collar bearings for absorbing the thrust loads produced by both controllable and fixed pitch propellers. The bearings come with a remote temperature sensor junction box, so the bearing can be connected to the ship’s central alarm system. If required, the bearing can be installed according to the “safe return to port” regulations.

The thrust pads are of a self-aligning type, and during installation an adjustment screw can be used for precise positioning and alignment.

The housing design offers maximum stiffness and ensures the proper load distribution directly from the thrust collar into the foundation.

The thrust bearings are very robust and reliable and almost maintenance free.