Assisted Bench Press MachineJARRED MORALES

JUNKUN MA

SPRING 2014

SOUTHEASTERN LOUISIANA UNIVERSITY

Negative Reps

Intensify workouts

Overload muscle groups

Control the tempo of the repetition for a 3-5 seconds rep count

25% more than you can lift

Eccentric phase causes muscle fiber damage

Assembly

Adjustable flat bench

45 pound barbell

two single acting cylinders

Front flange mount

U-bolts

Adjustable flat bench

Middle notch is the neutral position

The lower notch brings the bench closer to the floor

Accommodate for different arm lengths

Stroke Length

Laying forward grip reach

Drillis and Contini

Body segment lengths expressed as a fraction of body height H.

5’8’’(.438)=30in

Vary due to grip on the bar

Continuity Equation

Steady flow in a pipeline means weight flow rate is the same for all locations

Single inlet/outlet, no fluid added or withdrawn— Qi=Qe

Q=VA

Flow Characteristics

Nomographic chart

Volume Flow Rate

Required pump volume flow rate

Fluid volume swept out by the piston traveling through its stroke over a period of time

2in diameter

Schematic

Single Acting Cylinder

One port

Pressure from the fluid forces piston up

Force from weight pushes piston down

Pressure

Pmin=

hydraulic cylinder cushion

Prevents slamming from end to end

Plunger decelerates piston at the end of extension and retraction strokes

Creates a higher pressure

Cushion Equations

a cushion with a .75in height and 1in diameter

P

P

Directional Flow Control Valve

three way, two position, spring offset, pilot operated, directional control valve normally open

Pressure compensated flow control valve

The breaks

Maintain an essential constant flow rate with variations in inlet and load pressures

A spool is held by a set to set psi spring keeping it normally open

The type of pump

Requires a low pressure with a low volume flow rate

Ignoring OHP

Type of oil

Pressure Regulator

Connected between the pump and the DCV

Pressure changes due to variation in amount of weight being lifted

Can be adjusted to change amount of assistance

Check Valve

Between the pressure regulator and directional control valve

Prevents flow from flowing back to the regulator

Accumulator

Nitrogen filled bladder

Elastic barrier is between oil and gas

Safety mechanism

The volume decreasing in gas, causes an increase in stored energy

Reservoir

Storage space for excess fluid

Way of filtering

Metal chips, sludge, and water will be removed from oil

High enough oil level to prevent whirlpool effect

Surface area for heat dissipation and air space for thermal expansion

Conclusion/Future Design

Replaces need for assistance and most of the bench press assembly

Monitored the rate at which the cylinder descends, using a pressure compensated fcv

Applicable for different ranges of weight and people

Could have used a double acting cylinder with a four way, two direction control valve and eliminated the need of the weights

Thank you

Dr. Junkun Ma

Mr. James Stutts