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HURTH – HSW – HBW – IRM – BW Marine Gearboxes

All of these ‘replaced’ designations for marine transmissions now fall under the banner of  ‘ZF’.

There is still some confusion in the field relating to the early designations and we receive many contacts from owners and operators seeking information and spare parts.

We are here to help, so please do not hesitate to get in touch, if we can help, we will help.

The quality built into the early boxes is reflected in the age and condition of many of the units which we come across, rarely are they just’ worn out’.

It seems to take a serious regime of neglect, or a catastrophic accident, to put the old units beyond  economical repair. Some of the units we come into contact with are 25 – 30 years old, and still ‘going strong’!!

Today,  ZF continues to uphold the  tradition for quality of construction and coupled with advanced materials and manufacturing methods, operators can continue to have real confidence in the ZF product.

To clarify :

The original HURTH marque covered the  HBW & HSW gearboxes from HBW 40 to HSW 800 and these now translate into the ZF M and ZF models.

For example – HBW 12 mechanical gearbox becomes  ZF 12M. HSW 25 Hydraulic clutch becomes ZF25.

There have been changes over the transition period so always best to check..

Lubricant used in all of these models is ‘in the majority of cases’ ATF.

Always best to check. Incorrect lubrication can wreck your gearbox!!!

The original IRM marque covered gearbox models from IRM 220 to IRM 350. This series now translates into ZF models .

For example – IRM 220 becomes ZF 220. IRM 325 becomes ZF 320.

The additional letters and numbers attached to the stem no e.g., ZF220 V or ZF220A indicate the configuration of the input and output shafts.

ZF220V = Output shaft under input shaft. Vee configuration.

ZF220A = Down angle output shaft.

Lubricant used in these models ‘in the majority of cases’, SAE 30 or SAE 40 dependent on the area of the world where the gearbox is to go into service.

These oils are ‘straight’, not ‘multigrade’.

Always best to check. Incorrect lubrication can wreck your gearbox!!!

The BW marque relates, in general, to the larger gearboxes – Commercial , Large pleasure craft. The BW designation has now become ZF. e.g.

BW 165 becomes ZF 650.

BW 195 becomes ZF1950.

When dealing with this range of gearboxes – always best to consult.

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