gearbox "duty ratings" - what is it ?

[vacendak]

ran into this notion when choosing a new transmission:
looking into ZF25A specs, found a table of gearbox "duties":
(Pleasure/Light/Medium/Continuous):

http://www.simplicity-marine.com/pdf/ZF/ZF_25_A.pdf

Same with Technodrive.

Does it mean that there are different kinds of same model for each kind of application ?
Like, you know - "Pleasure" with Aluminum body and "Continuous" with Titanium

Gurus, don't laugh, please !
I know that it sounds like "Complete Idiot's Question" but could not find the answer !
Local NANNI dealer never answered this... and since then does not answer me at all...

[Sailmonkey]

All it boils down to is the amount of use and at what speed you plan to use the gear.

The same gear has a (hypothetical) pleasure rating of 50hp @ 3600 rpm for typical yearly hours of less than 250.

The gear will also be warrantied for commercial applications if the total input is say 25hp @ 1800 rpm and 10000 hours per year.

Really it boils down to longevity of the gear

[vacendak]

Originally Posted by Sailmonkey

All it boils down to is the amount of use and at what speed you plan to use the gear.
The same gear has a (hypothetical) pleasure rating of 50hp @ 3600 rpm for typical yearly hours of less than 250.
The gear will also be warrantied for commercial applications if the total input is say 25hp @ 1800 rpm and 10000 hours per year.

I thought so, too. But the paper says:

Available for Pleasure, Light, Medium and Continuous Duty applications.

Sounds like there are ZF25A-Pleasure, ZF25A-Light etc. ?

[Cheechako]

Engines too... pleasure rating for HP and RPM's are differ than continuous ratings...

[beetle]

Originally Posted by vacendak

I thought so, too. But the paper says:

Available for Pleasure, Light, Medium and Continuous Duty applications.

Sounds like there are ZF25A-Pleasure, ZF25A-Light etc. ?

You should talk with Hurth about this, they will give you the information you're looking for and can specify for you which of their equipment will best suit your application.

From what I recall when purchasing my ZF V-drive transmission, there does not exist what you are describing (e.g., same transmission in various duty-rating flavors). What you need to do is decide what your application is and then select the transmission that meets the requirements. For a transmission it's mostly about cooling ability vs. weight vs. cost (plus the unit needs to fit into the space available).

As others have written, the issue is longevity of the transmission for a given power input and load. You would not specify a 'light' duty transmission for use in a continuous duty application, nor do you need to overspend for a continuous duty transmission if you're application is for occasional 'light' duty use.

- rob/beetle

[Sailmonkey]

Originally Posted by vacendak

I thought so, too. But the paper says: Available for Pleasure, Light, Medium and Continuous Duty applications. Sounds like there are ZF25A-Pleasure, ZF25A-Light etc. ?

All that means is that they will warranty the gear for x HP pleasure, and y HP continuous.

[StuM]

Originally Posted by vacendak

I thought so, too. But the paper says:

Available for Pleasure, Light, Medium and Continuous Duty applications.

Sounds like there are ZF25A-Pleasure, ZF25A-Light etc. ?

No it just means that it can be used in these different applications and they specify maximum torque and RPM for each.

Read the specs in that brochure. It tells you that if you are just using it intermittenly up to 500 hours per year with large variations of power, you can push up to 310Nm of torque through it at up to 5500 rpm(pleasure rating). However if you are running it continuously at a constant speed (continuous operation) it is only rated to transmit 164Nm of torque and run at a max rpm of 3200.

The same specs tell you essentially that you can use it on a 165HP engine in "pleasure use" mode, but if you are in "continuous use" mode, you should limit it to 40 - 55 HP through it, depending on operating revs.

[Blue Stocking]

If you REALLY want to upset the supplier, ask them to give you the WRITTEN conditions under which you will be protected in the event of failure. I bet you can't get it.
Much of this vague language is so that many claim issues can be BS'd into oblivion by the supplier.
How does the average boat owner/operator prove that the box has never been used in excess of it's sale category ?