Unequal drive trim movement
#11
Charter Member #232
Charter Member
Re: Unequal drive trim movement
Originally Posted by CObarry
I see an invention opportunity...what about a programmable, digitally controlled trim system? It could have a memory setting...push a button and both drives move to 6 in unison (or whatever). Also, a step function...push another button and both drives move by 1 either up or down. Push another button and both drives move all the way down. Just need a little venture capital...
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
Jon
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#12
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Re: Unequal drive trim movement
I see an invention opportunity...what about a programmable, digitally controlled trim system? It could have a memory setting...push a button and both drives move to 6 in unison (or whatever). Also, a step function...push another button and both drives move by 1 either up or down. Push another button and both drives move all the way down. Just need a little venture capital...
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 !!!!! It just takes the guts to pull the trigger
Ramb
#14
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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
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
#15
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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
http://www.offshoreonly.com/forums/s...ad.php?t=99410
Dana Marine has indicators .....
http://www.danamarineproducts.com/st...TOKEN=22545117
#16
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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
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
#17
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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.
#18
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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!
-Larry
When in doubt, just add more power!
-Larry