LEFT and RIGHT HAND rotation

[inventing_man]

Greetings, Who makes jet ski size complete aftermarket pump assemblies ?
Surely there must be someone who makes left and right hand rotation pumps somewhere.
To simplify a project I'm thinking on , a left and right hand matched pump set would be a real good thing. Housing and wear rings all the same , The impeller just needs to be machined the other way .

[marshmat]

I've never seen counter-rotating jet pumps before. There's no real handling or performance advantage to doing so- the net thrust of a jet drive is one simple force vector, no strange torques like you get with props. Building a reverse-rotation jet would involve a lot more than reversing the impeller blade direction; the intake and bowl chamber vanes are usually directional (they have to align the water flow with the impeller, then straighten it as it comes out), as are accessory drives, hydraulics and take-off ports. You'd have to mirror the entire pump assembly, and for no real benefit. Not to mention you now have close to double the tooling costs and a much larger spares inventory.
Why do you want counter-rotating jets?

[inventing_man]

Think of a horizontal drive motor ( like the way a front wheel drive car has the motor side ways under the hood) pulling a central shaft horizontally posed (like the way a drive shaft is located in a front wheel drive) and u joints coming off the shaft on each end to get the shaft direction in line to the pumps which are vertically posed with the boat. The pumps will need to be counter rotating. Other wise it will have to have 90 degree bevel gears to make the turn and change direction so all pumps turn the same way. Or at least one side will need a reversing gear 1 :1 to change the direction in a drive line set up. ( not shown) U joints and drive line will be a lot less mechanically involved to have to support than gears...If ... there were such animal as a L and R hand pump.
Why 2 pumps ? Redundancy and tunnel style hull.

[marshmat]

I was involved in some fairly detailed research recently regarding the U-joint vs. bevel gear options, for a 90 degree kink in a steering linkage. Two U-joints of any standard type will not give you a smooth 90-degree transition; to do that requires at least three (even the most flexible units get extremely cranky around 30-40 degrees). And U-joints need bearings on both sides- as you've drawn it you would need six to eight bearings to support the U-joint assemblies. With bevel gearboxes you have one mounting per side, integral bearings, and a safer and more reliable transmission. And you would have no need for a counter-rotating jetpump that does not exist. The first of your two drawings is definitely the better of the two options.

[inventing_man]

I agree , Can water be the source for cooling and lubricating these gears ? Or the standard oil box surrounding them ? or even open air .
I'm sure its the oil box , but just asking .

[Frosty]

Yes you would need CV joints ---AND by the time you have all this gear and drive train wieght will have totally destroyed any benefits you hope to achieve not to menton how far forward will the engine be at this stage.

The whole point of the jet and its popularity was because of its simplicity.

Your first drawing would not be too bad if you sited the engine in between the two jets, and did away with the belt drive.

[stonebreaker]

Why don't you just use an entire front wheel drive engine and drivetrain? Most of the engineering would already be done, and then all you'd have to do is turn the final corner.

Maybe you should research unlimited tractor pullers. Those guys run multiple engines into one driveshaft. You're doing the same basic thing in reverse.

[stonebreaker]

Here you go. Notice three separate rotor blades on this mower are driven by one power input.

[azs]

twin jets have been driven by one motor with simple chain or toothed belt drive with much greater simplicity, and no need for reverse rotation. Check out this boat setup http://www.youtube.com/watch?v=KUX347RsFGg

[mydauphin]

Seriously, one other issue is that jet drives eat up a lot of power. You are more likely to see multiple engines to one jet than the other way around.