What do you think of this idea for power tilt/trim?

[Mark42]

I can't find a used power tilt/trim unit for my 40hp that is within my price range. So what do you think of this setup:<br /><br />I get one of these 12 v trim tab hydraulic pumps (400psi, $187) <br /><br />

<br /><br />And one of these trim tab hydraulic cylinders (also rated 400psi, $57)<br /><br />

<br /><br />And I replace the manual tilt cylinder with the trim tab cylinder, hook it up to the trim tab pump, a few feet of wire and switches, and I should have a working brand new hydraulic power tilt/trim unit for my 40hp. <br /><br />I figure that the trim tab cylinder should be able to lift the 180lbs motor. At 400psi pressure and cylinders being about 1.5" bore that gives about 1.7 sq inches of area, or 680lbs of lifting force. Worse case two cylinders could be used (they should fit in the old manual cylinder location).<br /><br />The nice part about using these parts is they are all marine grade and should perform well on the water. To protect the investment and the outboard, the cylinders would be mounted with shear pins to break away easily if an obstruction (aka big rock) was struck at speed.<br /><br />What I like about this idea is: <br /><br />1. It seems like a lot less work than trying to fit an available used trim system from a different make or model outboard.<br />2. The parts are new so there are no used parts failure or life expectancy issues.<br /><br />3. The parts are marine quality so they will hold up better than using one of these linear actuators that I have been toying around with that weren't meant for marine use (165lbs thrust, 12v, $119)

<br /><br />4. Shouldn't take much to mate the cylinders to the outboard. <br /><br />5. If those cylinders can hold trim tabs at an angle on a big boat against the resistance of water while going 40mph, then they should also be able to work as a motor trim system also.<br /><br />6. It is an all brand new system (warrantee!) for less than 2/3 the price of a used (buyer beware!) tilt/trim for the 40hp.<br /><br />So wadda think?<br /><br /><br />Edit:<br /><br />BTW, does anyone know what the stroke is on these big trim tab cylinders? The ones I show are replacements for Trim Master or Bennett Systems. Also, the collapsed dimension and diameter would be helpfull. <br /><br />Thanks!

 

[alden135]

Re: What do you think of this idea for power tilt/trim?

Hey Mark,<br /><br />I'm no mathmasurgeon, but don't you need to also add the thrust force in the calculations? I would think it would be some portion of pivot weight + the thrust force of the engine. I don't know, just asking.

 

[Mark42]

Re: What do you think of this idea for power tilt/trim?

I really don't know. That's why I post this stuff here, I hope that someone will point out my flaws. Even if it doesn't have the power to act as a trim sysem while underway, it should still be able to perform the tilt function, right? <br /><br />I have been looking around and found other mini 12v pump systems by Oildyne (parker company) that run up to 3000psi. Need to find a retailer to get prices on their systems.<br /><br />Also found some of the merc cruiser power tilt/trim cylinders might work too. A bit bigger to handle the thrust of those big v8's. <br /><br />I think these area all single acting cylinders, meaning that the cylinder expands with pressure, but relies on the resistance to push them back. That might work OK for me too. Gravity and propeler thrust should work in my favor.

 

[gspig]

Re: What do you think of this idea for power tilt/trim?

Another consideration is that the trim pump you want to use have a valve. You need a way to lock the system or the thrust force will push the cylinder.

 

[Chris1956]

Re: What do you think of this idea for power tilt/trim?

Mark42, There is a difference between a trim tab hydraulic system and a trim/tilt setup. The trim tab hydraulics only push the tabs down. A spring pulls them back up. If you rig up the system you have described on your outboard, when you cut throttle, your motor may pop up, since there is no downward hydraulic pressure.<br />You may be able to get around this limitation, however,with proper operation of the motor.

 

[ob15]

Re: What do you think of this idea for power tilt/trim?

I'm not sure if it will work or not. I know that my 1989 J50 unit operates on much higher pressure than that pump and the cylinder is larger. I would try to calculate the force from the motor. A formula for that was mentioned in a post a few day ago I think (don't remember what forum though). You may find that the forward thrust of the motor is pretty high and then the angles the rams would be at may not hold the forces. The highest forces are when the motor is all the way down. It's much higher than just the motor weight because of the angles. Plus the stroke length of those units may not be enough. <br /><br />I don’t want to rain on your parade, but I just don’t think it’s going to work. I hope someone with some mechanical, hydraulic and/or structural experience comes along and adds input. I think it’s a pretty cool idea and hope that maybe you can get something figured out. Good luck!

 

[G DANE]

Re: What do you think of this idea for power tilt/trim?

I would get a used unit on ebay, much cheaper and they are easyer to get during winther.

 

[Mark42]

Re: What do you think of this idea for power tilt/trim?

I think you guys are right about the trim tab cylinder not being the right part. I did find a company that makes OEM tilt/trim motors and has a generic 12v motor/pump unit pushing about 3000 psi. Its reversable (I think). If I can find a generic aftermarket ram of the right size it should work same as the real thing. <br /><br />G Dane, the problem I have is that a used unit on ebay for the 40/50hp 1993 model is 1) hard to find. 2) usually sells for over $400. Plus there is that whole "used parts" issue of "how used is it?" Will it last one week, one season, or 5 seasons? If I could find one reasonably priced, I would snatch it up in a moment. But at $400 and up, I would rather spend my money on new equipment and know what i have.

 

[G DANE]

Re: What do you think of this idea for power tilt/trim?

Often it is cheaper to get a blown motor to get it from. The twin looper 50 and 60 are identical to yours, and quite a bit of the 60 HP bite the dust as the output is high compared to CI. A used unit can be rebuild if neccesary, I agree in that 400$ is much to gamble with, at least in my budget.

 

[JB]

Re: What do you think of this idea for power tilt/trim?

Outboard Non-repair. This is a no engines forum

 

[AMD Rules]

Re: What do you think of this idea for power tilt/trim?

Thread is better suited for the building forum where most of the 'creative minds' congregate.<br /><br /><br />Mark,<br /><br />If you do build you're own tilt/trim system don't forget to add the upper limit switch... You would have a pretty sad face if your cowling and splashwell met under those circumstances.... <crunch>

 

[Mark42]

Re: What do you think of this idea for power tilt/trim?

AMD, Your right about the need for limit switches. With the electric linear actuators I was looking at earlier they were available with the switches built in and adjustable. I got the idea to look at electric actuators from the Panther brand tilt they offer for motors up to 35hp. I figured I might be able to find an 'off the shelf' actuator that would physically fit and have the power to lift my motor. But when the actuators get into the high power units they get pricy too. Plus the marine grade actuators are designed for lower power usage like the deep sea robots and remote control search units. I did find one unit that fit the bill, called them up and they said two weeks wait on the build, then figure roughtly $600 for one. <br /><br />So that put me back into the hydraulic arena. I don't have much knowledge of hydraulics, but I'm learning from my search for parts what is involved in making a basic hydraulic circuit with controls. <br /><br />There is still the electro hydraulic units that are basically an electric motor/pump/cylinder combo. But I haven't been able to get prices or find one that will fit in the space available.<br /><br />Hey JB,<br /> I can understand your moving the thread because it would seem it's about outboards, but really its about designing and building a custom tilt/trim unit. That's why I started it in the Restoration/Building forum. <br /><br />At any rate, anyone who has knowledge of hydraulics and/or online suppliers of hydraulic parts to browse and/or a webiste that describes basic hydraulic circuit design, please chime in! I think I'v exhausted the scope of yahoo and google to help me do research!!! <br /><br />See, now that the basement is done, the boat is put away for the winter, I have time to spend on this project. Maybe I can have it done by spring?<br /><br />Thanks,<br /><br />Mark.

 

[phatmanmike]

Re: What do you think of this idea for power tilt/trim?

why not try to find a used version of this:<br /><br /> http://cgi.ebay.com/ebaymotors/NEW-...593981067QQcategoryZ50439QQrdZ1QQcmdZViewItem

 

[Mark42]

Re: What do you think of this idea for power tilt/trim?

'Cuze my steering cable won't reach.

 

[G DANE]

Re: What do you think of this idea for power tilt/trim?

My brotherinlaw once had a 60 HP, similar to yours, the former owner of the boat put a Merc Trim/tilt on it, they have seperate pump and cylinder, and go cheap on Ebay. Why not go that route, you will get components that operate with proper torque, and are made for the environment.

 

[G DANE]

Re: What do you think of this idea for power tilt/trim?

Wait a minute, isnt this the right one ??? HURRY UP http://cgi.ebay.com/ebaymotors/OMC-...592607478QQcategoryZ50439QQrdZ1QQcmdZViewItem

 

[Mark42]

Re: What do you think of this idea for power tilt/trim?

G Dane, <br /><br />I don't know why I didn't see that earlier. I have been checking e-bay every day. But, I don't know if that would fit from the looks of it. <br /><br />I'll keep my eyes peeled.<br /><br />I did find that e-bay has a load of hydraulic cylinders that are the right size.<br /><br />Edit:<br /><br />Thanks for the advice on Merc units. I can see how they could be easily adapted. <br /><br />I think I'm getting obsessive/compulsive about tilt/trim.

 

[phatmanmike]

Re: What do you think of this idea for power tilt/trim?

why wont your steering cable fit? is it too short?

 

[tgissel]

Re: What do you think of this idea for power tilt/trim?

http://cgi.ebay.com/ebaymotors/JOHN...594144508QQcategoryZ50439QQrdZ1QQcmdZViewItem <br /><br />Mark try this link found it on E-BAY<br />Good luck

 

[dafox99]

Re: What do you think of this idea for power tilt/trim?

My dad, who worked at Cessna and Beech in the 70's and 80's, used a flap actuator. Had a handle by the throttle that he would pump to raise engine (even under load), and a button at the top to lower. It was remarkably precise, but I doubt finding one of those that would fit and cost less is pretty much impossible .. just thought I'd share a cool story.<br /><br />I had posted the hp/thrust equation, but it would only apply to a perpendicular thrust on the transom. 1 hp = 33,000 ft-lbs/min. This is essentially speed (ft/min) X thrust (lbs). Take that times .01136 to get 1 hp = 375 miles-lbs/hour. So, you can take your hp, multiply by 375 miles-lbs/hour and divide by your speed (miles/hour) and you have the thrust (lbs). If your 50hp motor pushes your boat 30 mph, you have 50 X 375 / 30 = 625 lbs of force applied perpendicularly to your transom. Note that only works for "working" props, as you would multiply this by your prop efficiency (typically 60% to 70% while going down the lake with no acceleration) to get a more precise solution. Prop efficiency starts at 0 as you can spin the prop very fast before the boat starts to move (lots of power, no speed), and if you look at the equation, if mph is 0, unless you take the prop efficiency into consideration, you have infinite thrust. So, the actual thrust during acceleration depends on prop efficiency, which is very low at first, and begins to improve as slipage decreases.<br /><br />This force could be considerably different than the force on your cylinders as we would need to know the geometry of the transom/engine/mount to determine that.