2015
Automated Marine
Trailer Jack
RYAN SCHECH
SENIOR DESIGN 494
PROPOSAL DOCUMENT
ADVISOR: DR. JUNKUN MA
PROFESSOR: DR. KOUTSOUGERAS
| February 24, 2015
TABLE OF CONTENTS:
Abstract ……………………………………………………………………... 2
Introduction …………………………………………………………………. 2
Objectives and Engineering Methodology………...……….…………………2
Deliverables ………………………………………………….……….………5
Timeline………………………………………………………………….…...5
Figure 1 provided by: www.k-ksystems.com
1
Abstract:
The scope of this project is to eliminate the process of manually operating a trailer jack.
The idea is to design a system that will easily raise or lower the tongue of a boat trailer by a push
of a button. The normal process, of raising or lower a trailer, involves the manual procedure of
cranking a handle in a circular motion. This process is solely dependent upon how fast or slow
the operator turns the handle of the jack. In some cases, the load on the jack is quite substantial
and requires a lot of force to crank the handle in order to raise the trailer. This will cause
undesirable discomfort and fatigue to the operator. Designing an automated jack will eliminate
this work and make the process of lifting a trailer much easier.
Introduction:
To achieve the goal of designing an automated trailer jack, several variables and
parameters need to be identified. After obtaining a suitable design, the components and parts
must be identified and distinguished. Some parts will consist of available parts (market ready),
but some will need to be custom. These custom parts require further analysis to determine the
optimum design. The analysis will consist of various calculations and software modeling. The
overall design must be able to withstand the load of approximately 1500lbs for smaller
recreational boats. For use with commercial size vessels, the design will need modification in
order to accommodate the excess load.
Objectives and Engineering Methodology:
Since the trailer jack is concerned with boat trailers specifically, we need to first evaluate
the design for most boat trailers. Common trailers used for campers have what’s called an ‘A’
frame design at the tongue of the trailer. Unlike a camper trailer or utility trailers, most
recreational boat trailers don’t utilize the ‘A’ frame design. The tongues of boat trailers are
designed with a single linear piece of metal, usually having a square or circular cross section. We
start here to determine how to mount the jack to the boat trailer. Most manual jacks are side
2
mounted so they can be folded up to be parallel to the trailer frame. This helps prevent dragging
the ground during the launching process. These side mounts are available on the market and can
be bought separately. I will chose an appropriate one from the market that will work with the
automated jack.
I had two different designs in mind, one involving a side mount and one that would be
mounted on top of the trailer frame. The problem with the design mounted on top comes when
launching. If a wheel were to be attached to the bottom of the jack (underneath the trailer frame)
it would drag during the launch. The best way for this design to work would be to eliminate the
wheel. I chose not to do this or this design because the wheel does serve as a vital part of the
trailer for multiple reasons.
The side mount design, that would be the better choose, possess its own challenges as
well. One consideration includes the fact that there is the possibility of becoming submerged
under water, either completely or partially, during launching. Another consideration is how the
wires will be connected to the motor controller without becoming too exposed or a nuisance to
the operator.
The following includes the component list along with detailed explanations of the
engineering methodologies needed to complete the designing of an automated trailer jack for
boat trailers.
‘Automated Trailer Jack Design’: Lift Capacity of 1,000 lbs (commonly used marine jack rating)

Snap-ring swivel marine ‘bolt-on’ mount (Available on the market)

Wheel assembly (6” diameter reinforced poly, available on the market)

Outer tube diameter 2” (market)

Inner tube diameter 1-3/4” (market)

Motor control (Arduino)

Load detection senor to protect the motor from excess loads
o Will need to write a program that will control the motor’s movement and
incorporate the sensor readings so that sensor can protect the motor from
overloading.

Pulley (find the available sizes on the market)
3

Motor sprocket (market)

Belt design (market)
o Select the sprocket and pulley in accordance with the belt design.

Motor selection
o Will need to complete a full analysis on the system to determine how much torque
is needed to establish the lifting motion.
o Once the forces acting on the system are known, I can then determine the sizes of
the gears and pulley (for speed reduction and availability on the market), motor
size, power required by the motor (to determine the power source).

Small bevel gear
o Determine the gear diameter and how to secure its position

Large bevel gear with long threaded shaft and fixed plate containing a bearing
o Will need to determine the gear diameter along with the thread count and pitch on
the driving shaft.
o The fixed plate will need a bearing to enable the rotation of the shaft, but will
need to eliminate up and down motion of the shaft.

Custom design a rod that will hold the small bevel gear and the pulley at fixed positions.
o Calculate the load being exerted on the shaft
o Determine the best material to use
o Determine the shaft diameter that will withstand the load
o Design bearings on the ends of the shaft for rotation. (These bearings will be a
part of the housing)

Design the housing of the motor, motor control, pulley assembly, rod, and gears.
o Mounting of the motor and rod containing the small bevel gear and pulley.
o Position of the motor controller along with the controls mounted on the outside of
the housing.
o Determine the materials to be used and the fabrication process
4
Deliverables:

Overall design of a suitable system

Designing the housing of the system

Analysis determining the sizes of the:

Motor

Pulley

Bevel gears

Threads

Stress analysis to determine the size of the rod

Modeling the characteristics involved on the rod in COMSOL

Developing a program (using Arduino) to control the motor

Modeling the Automated jack assembly in SolidWorks














Propose project idea…………………………………………...Jan. 27
Obtain two possible design sketches for trailer jack…………..Feb. 3
Compile a detailed list of components and deliverables .……..Feb. 10
Project approval………………………………………………..Feb. 24
Project proposal document……………………………………..Feb. 26
Stress analysis of system ……...……………………………….Mar. 6
COMSOL modeling of parts under load………………………..Mar. 13
Selection of motor and rods.……………………………………Mar. 20
Speed reduction analysis to determine part sizes……………….Mar. 27
Selection of pulley, sprocket, and belt type……………………..Apr. 3
Order the needed parts…………………………………………..Apr. 4
Write program to control and protect motor…………………….Apr.10
Develop model of project in SolidWorks……………………….Apr. 17
Assemble together and test results………………………………May 1
Time Line:
5