Basic question about tilt/trim on 1993 Force 150

[HotTommy]

Winter is taking one more shot as us here, so I'm inside thinking about future tasks rather than outside doing any of them. One of the jobs on my list is to repair the tilt / trim system on my 1993 Force 150. It was inop when I bought it in part because the previous owner had broken off two mounting bolts while trying to fix it. Other than that, I have not yet tried to figure out what needs fixing. But I have spent some time studying the wiring diagram and info in the Factory Service Manual.

Here's my question. I see that there is one hydraulic cylinder for trim and another for tilt. It also appears that there is only one hydraulic pump and one electric switch (on the throttle) to command up/down. How does the system determine which cylinder gets the hydraulic fluid when the switch is activated? Is there any reason for the operator to know or care which cylinder is moving the engine?

 

[Frank Acampora]

Re: Basic question about tilt/trim on 1993 Force 150

Because the trim cylinder has greater area it has much greater hydraulic advantage. It also has a much greater mechanical advantage. SO: When hydraulic pressure is sent to both cylinders in the UP mode, the trim cylinder moves first. When it reaches the limit of its travel, if the engine is not under power or if the boat is on the trailer, then the tilt cylinder will start to move.

Because of the lower hydraulic and mechanical advantage, the tilt cylinder will not move the engine while under power. Additionally, if you do tilt the engine and apply power at more than about 1000-1500 RPM, there are relief valves in the cylinder and pump which will let the engine drop onto the trim ram.

When hydraulic pressure is sent to the cylinders in the DOWN mode, the tilt cylinder will move first until the engine is against the trim ram then the trim will continue to move inward. Because of the increased hydraulic advantage, sometimes in DOWN mode with the engine tilted, both cylinders will move at the same time.

As the operator, you do not care: As long as the engine trims under power and tilts on the trailer you are happy.

 

[HotTommy]

Re: Basic question about tilt/trim on 1993 Force 150

Thank you for the complete and concise explanation.