Gearbox vs. Transmission?

While working down in the British Virgin Islands years back I noticed our Commonwealth cousins (Brits, Aussies, Kiwis, etc.) used the word "Gearbox" for what I call a "transmission." Is there a difference, or is it another of those many examples of Americans and Brits being, as Churchill said, "two peoples seperated by a common language?"

I have always called it a "gear reduction unit".

From what I have read over the years the "proper" term for the gearbox/transmission behind a marine engine is "marine gear." I have no clue if that is a US term, an industry term, or what. IIRC all the books and articles I've read that used that term were older publications, so perhaps the term has fallen out of favor by now.

However if you Google "marine gear" you will get a number of hits for marine "transmission" service and repair outfits, some of whom use the term "marine gear" in their company name or website.

So far our BW Velvet drive marine gears have given us no problems so I've had little reason to discuss them much with our local diesel shop. But on the few occasions I have I've referred to them as "marine gears" and they knew exactly what I was talking about.

Maybe an industry pro like Rick B can confirm that this term is or isn't used these days.

I think I actually know the answer to the gearbox/transmission question.

A transmission is found on a vehicle that needs the power to be transmitted from the engine (or motor) to the drive shaft that in turn transmits it to the driving wheels or propeller.

A gearbox is the housing for the gears or the housing and the gears within the housing. But to be sure it's a housing w gears within and can be found on equipment in factories, farming equipment, Pellet stoves, cranes or even bakeries. The gearbox holds the gears in place (very specific places) with shafts and is basically employed where the speed of a shaft needs to be increased or decreased. The box usually holds the lube oil too.

Taking a stab at it I obviously don't know what the difference is.

I think there are transmissions w/o gears.


I was hoping Rick would give us some help on all the oil questions.

Gear boxes (to me) are the vernacular catch all for torque/speed reducing/increasing, or directional changing (and combinations thereof), using gearing inside housing.

Transmissions (to me) are "gear boxes" with different ratios available, whether manually or automatically changed.

However power transmissions in industry usually involve belts and sheaves, sprockets and chains. Go figure.

I use "marine gear" for my boats application.

Didn't know Rick B. was gone. That's too bad. He had lots of info (not opinion) to offer. Probably one of the few marine engineers on this board.

Northern Spy said:

Didn't know Rick B. was gone. That's too bad.

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Rick comes and goes as his business demands dictate. I would not be surprised to see him come back for awhile before he heads out again.

A gear box to me is where the shaft speed is geared to slow up the shaft revolutions of the engine in relation to the propeller. Since my boat has one forward gear and one reverse gear as well as neutral, I consider the device between engine and propeller shaft to be a transmission even though the gears reduce shaft speed between engine and propeller.

The "back end" of my transmission/gear box, whatever.

does anyone have an owner's manual that says transmission?

Regarding Rick, Marin is spot on. Rick is alive and well on other sites where tech knowledge trumps PC.

sunchaser said:

does anyone have an owner's manual that says transmission?

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Yes. The operations manual for the Borg Warner Velvet Drive uses the term "Marine Transmission" throughout the manual.

Probably the same difference as between the trunk of a car and the boot of a car, windshield - wind screen, etc.

I've seen many posts here where it was referred to as a "tranny"!

My Volvo manual calls it a "reverse gear". Seriously.

Ron the expression "reverse gear" was common it the 50s and 60s. The basic reason for having a "gear" was to have a way of backing up or stopping. Most gears were basically just direct drive probably in the 30s and 40s. The engines turned about the same speed as our propeller shafts do now. Then with the higher reving engines the focus went to gear reduction. Now we assume any "gear" will have reverse. I've heard them called re-drives ect ect but fortunately all the names are self explanatory so no one's likely to get confused.

manyboats said:

Ron the expression "reverse gear" was common it the 50s and 60s. The basic reason for having a "gear" was to have a way of backing up or stopping. Most gears were basically just direct drive probably in the 30s and 40s. The engines turned about the same speed as our propeller shafts do now. Then with the higher reving engines the focus went to gear reduction. Now we assume any "gear" will have reverse. I've heard them called re-drives ect ect but fortunately all the names are self explanatory so no one's likely to get confused.

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Yes, I've heard that before. I have found though, that using the term "reverse gear" in a conversation or a web posting causes nothing but confusion so I just call it a transmission.

Marin said:

Maybe an industry pro like Rick B can confirm that this term is or isn't used these days.

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Folks - there's been much speculation and discussion on this thread about the where-abouts of Rick B including some really harsh comments. We've removed the bulk of these for a number of reasons. Many were just mean, all of them were off topic (this is a thread about transmissions) and frankly some details of member accounts are private. We tell folks that we'll keep much of the info included with their membership private and we intend to honor that promise. Please remember that even if a member isn't logged in they can still READ every post you make.

Let's get back on topic and leave the speculation and cutting comments behind. Personal attacks on others will not be tolerated. Challenge others' points of view and opinions, but do so respectfully and thoughtfully.

Now, back to gearboxes.....

markpierce said:

A gear box to me is where the shaft speed is geared to slow up the shaft revolutions of the engine in relation to the propeller. Since my boat has one forward gear and one reverse gear as well as neutral, I consider the device between engine and propeller shaft to be a transmission even though the gears reduce shaft speed between engine and propeller.

The "back end" of my transmi

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Your engine room looks cleaner than many operating theaters I've seen. Makes me feel guilty about my own, but thanks for the inspiration amigo!

manyboats said:

Ron the expression "reverse gear" was common it the 50s and 60s. The basic reason for having a "gear" was to have a way of backing up or stopping. Most gears were basically just direct drive probably in the 30s and 40s............. .

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I've read about older boats that were direct drive and in order to back up, the engine was started and run in the opposite rotation. I'll bet "back and fill" would be a real trick in one of these.

Well I have been a Marine Engineer for well over 40 years, Engineer Class 1 Steam & Motor since 1975 and still at sea.
Also I am from the Aus/British side of things and to me they have always been referred to as gearboxes even if mounted behind a 40,000 HP steam turbine.
In the automotive world I would refer to an automatic gearbox as an auto transmission.
I think the transmission thing is more American.
Same as the terms wheel and propeller, to most of us a wheel is on a vehicle of some sort.
Cheers
Benn

My Great Grandfather ran a 40' (maybe 45 ?) trawler (a real one) out of Fraserburgh (North of Aberdeen) with a single cylinder direct drive diesel. As a kid in the 50's I remember my dad taking instructions from my great grandfather at the wheel as he stopped the diesel and spun the flywheel by hand in the opposite direction to stop the boat.

Well I used to use the word Tranny but i learnt that you need to be very careful when using that word to someone that doesn't know what it means.
My mum rung me the other day to say hi and she asked what I was doing. I said "I was lubing up my tranny". A silence ensued and was followed by "well no matter what, know we love you and are happy if you're happy" not really paying attention to what she had said, i replied " yep I'm really happy, she looks great". it wasn't till After she asked how long this had been going on for and asked for a name and where we met that it clicked. She was thinking I meant transvestite and not transmission. I quickly dispelled any thoughts of this and reassured her I was very happily engaged to my fiancé and that I liked women not men lol.

So I guess I'll be using the word gearbox from now on and I'll be sure to listen more intently when my mum calls lol

Hendo,
You should have carried that one on a bit farther. Where's you usual sense of humor?
"I know it's a shock mom but what do you think?"
Yea your're right ......... too mean.

manyboats said:

Hendo,
You should have carried that one on a bit farther. Where's you usual sense of humor?
"I know it's a shock mom but what do you think?"
Yea your're right ......... too mean.

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Hahaha took me an hour to convince her with what I had said lol. I wasn't thinking straight. I was in damage control lol ;-)

Captain K said:

While working down in the British Virgin Islands years back I noticed our Commonwealth cousins (Brits, Aussies, Kiwis, etc.) used the word "Gearbox" for what I call a "transmission." Is there a difference, or is it another of those many examples of Americans and Brits being, as Churchill said, "two peoples seperated by a common language?"

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Definitely, in NZ and Aussie 'gearbox' and 'transmission' are interchangeable terms...

many call it a "Marine Gear"

Phil Fill said:

As for the old direct drives with NO metal gear thing, it was surprising how quickly stopping the engine, flipping the cam cog and starting the engine can be done. Most of the engine are slow under 300 RPM so they stop fairly quickly, and there was a lever, chain/cable to the cam cog. May be a couple seconds longer than boats with the gear thingy as it has to slow enough before shifting.

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Still, it must have been very difficult to negotiate a tight marina with that system.

Phil Fill said:

As for the old direct drives with NO metal gear thing, it was surprising how quickly stopping the engine, flipping the cam cog and starting the engine can be done. Most of the engine are slow under 300 RPM so they stop fairly quickly, and there was a lever, chain/cable to the cam cog. May be a couple seconds longer than boats with the gear thingy as it has to slow enough before shifting.

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So my husband was a sea scout and I don't know the details but the boat had to be shifted from forward to reverse in the engine room. There were some levers at the helm that the helmsman would move back and forth to indicate what we wanted the person on the engine room to do. They make some kind of "Ching Ching" noise and the person below repeats the message back to show they received it correctly. They were coming into a marina in San Francisco and the helmsman sent the signal to change from forward to reverse. The engine room responded but the boat kept moving forward. He signaled again "all reverse full". The young sea scout in the engine room was confused and thought the message was "all ahead full". They ended up crashing into a docked submarine. true story.

rwidman said:

Still, it must have been very difficult to negotiate a tight marina with that system.

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Yes it is, but they tend to be mooored in commercial areas/docks, so pumping and banging into each other is not a big deal. You should see them come up against a dock. When they came in a little to fast/hard we sat down on the dock because you would be knocked down. Well, first we ran as safe distance.

Last night my wife was watching a 70+ ft steel converted tug dock, it had a gear box, has a dozen tires hanging from the siide and he came hard against the dock. She wachted for quite a while, so I asked her what was she was watching, "Oh, just the tug docking." Followed by, "We should have a couple young male to crew and help us dock." I looked out the window and two 20-30 ish males where tucking and pulling on the line. Ha right! Waching the tug boat dock? !

Its not uncommon on the larger pleasure and commercila docks that other come help to line in the boat as we know what a puckker factor docking can be.

Hendo 78..rich story amigo! Love it!! Wish I was that quick on my feet. No wonder my Limey pals call it "Gearbox." So will I from now on. Cheers!

Phil Fill said:

........... Its not uncommon on the larger pleasure and commercila docks that other come help to line in the boat as we know what a puckker factor docking can be.

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Docking help is great and I personally appreciate it but some folks have posted on this forum that they don't want anyone helping. To each his/her own, I suppose.

There's a guy a few slips down from me who is so particular about docking or casting off that most of us hide in our boats when we see him coming. Being yelled at is a big disincentive for helping.

Captain K said:

Hendo 78..rich story amigo! Love it!! Wish I was that quick on my feet. No wonder my Limey pals call it "Gearbox." So will I from now on. Cheers!

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;-)