I have two hurth Hsw 250 A gear boxes in my boat and I would like to know there ratio, the problem is that there is no name plates on them . Can some one tell me how can I find the ratio please .
Thanks
normally they are 2:1
the instructors manual should have
Quote from: offken on September 08, 2009, 19:34:16 CET
I have two hurth Hsw 250 A gear boxes in my boat and I would like to know there ratio, the problem is that there is no name plates on them . Can some one tell me how can I find the ratio please .
Thanks
Hi offken, there are two available options for that gearbox. In the first case the forward and reverse ratio is the same namely 2.737 : 1. The second configuration you have different forward and reverse ratios, 2.737 : 1 and 2.227 : 1. Which ratio is used as forward in this case depends if you are using a right hand or left hand prop.
Although most gearboxes for light duty and pleasure are 2:1 or close enough you cannot assume anything. Each boat/prop/engine setup is unique.
turn the main shaft one full rotation and see when looking at the prop how much it will turn.
Here is the spec sheet for your gearbox. Note that Hurth changed all the gearbox model names and this is what your HSW 250 A is equivalent to today.