Re: Unequal drive trim movement
 

Bennet makes something like that.

The problem is that the likelyhood that both pumps pump at the same preasure is very low. We found with the race boat that when we swapped over to the high performance pumps that they trimmed at the same rate. I think that they probably build them to a much higher tollerance. Another thing to check is that your rams are not bound up at all. The rams tend to chalk up in a part called the scraper and a little behind the scraper and this makes it harder for the rams to move. You can take the ends of your rams off the drives and twist them and see if they all twist with the same effort. You could also put on a throttle that has twin buttons on the handle :D

Jon

Re: Unequal drive trim movement
 

I have been thinking about this actually. I work in prod dev in the auto industry. we supply about 1/3 of all seating systems in the US new cars. we have seat memory. ( and morror, and steering column) i could incorporated this logic box with a linear potentiometer for each drive ram and have up to 3 position presets that you could reasign whenever you want. ( down for planning off, best trim for speed, trailer one touch?) you could even make our keyless remote work and show off your setup from the dock :D

The good thinkg about the solution i have been pondering is that even if the pumps traveled at different speed, they would stop independently once they reached their own setpoint...... so what if one gets there .8 seconds before the other...........

I think I may have a post here about it somewhere.......

but it is on the list behind poor man's digital trim indicator and straight through silent thunder mod (which i am doing presently)


hey... remember how tomcat started with his intercooler idea? ...look at him now... just look at him now !!!!! :woohoo: It just takes the guts to pull the trigger

Ramb

Re: Unequal drive trim movement
 

Ramb .... you do this .... great great idea .... BIG thing is drive and Tab indication by wire !!!! look at less clutter ...less weight (maybe) ...

Re: Unequal drive trim movement
 

Off the....

I assume you mean indicate by electrical wire, not push pull cable. that is my plan for poor mans digital indicators......
I want to find a high caliber rotational potentiometer or encoder( replace the merc puck) then use industry standard 2" digital volt meters in the spots for the merc guages and a solid state voltage regulator/supply . this can be calibrated to read 1 - 10Volt and ta da !!! digital readout to .1 Volt resolution for trim position.

this voltage feed can then also be used for the memory location....

I have not found a small enough package encoder that is water tight... still searching the industry..... the digital volt meters are off the shelf, and the memory logic boxes i can modify from our seat memory modules...........at least for my prototype

Ramb

Re: Unequal drive trim movement
 

Another Similar thread .....

http://www.offshoreonly.com/forums/s...ad.php?t=99410

Dana Marine has indicators .....

http://www.danamarineproducts.com/st...TOKEN=22545117

Re: Unequal drive trim movement
 

Most of the problem lies in the inherent design of the hydraulic trim pump and it's associated check valves, hoses, and pistons. Each pump will have slightly different tolerances of rotating parts, which will allow a certain amount of 'leakage' past the vanes. This leakage results in slightly less volume being pumped per rpm. You also have friction in the piston assemblies that will be slightly different, and possibly slow the travel rate.

IMHO the way to solve this issue is to have a single pump pressure and capacity that significantly exceeds what the pistons basic requirements are. Then the pump's excess capacity can be throttled back slightly to have the exact flowrate under ALL loading conditions (fluid viscosity, friction, propload, etc.) without blowing out the piston seals. This pump would be used for BOTH drives and just controlled using two directional solenoid control valves.

Just my $.02

-Larry

Re: Unequal drive trim movement
 

Larry, incorporating some type of accumulator would also help keep a consistent pressure but you continue to add weight and complexity to the package the more you "engineer" it. :D

Re: Unequal drive trim movement
 

Yes it would, but as you indicated it will add weight. The accumulator will not add pressure (that is a factor of the pump and relief valve setting), but it will help keep it stable and keep the volume fairly consistent. I think, with the right pump and motor combo, there would not be a need for an accumulator in the system.

When in doubt, just add more power! :D :D :rolleyes:

-Larry

Re: Unequal drive trim movement
 

well ...... he elminated one pump .....why not bump it up some more and use one pump for drives .....AND tabs

Re: Unequal drive trim movement
 

EXCELLENT SUGGESTION!!

Just add another few solenoids and check valves and BINGO....A kickass hydraulic system! :D :D