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Analysis And Design of Custom

Hydraulic Clutch Pedal

Zachariah John

Henry Helfman

Bernadette Bautista

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Previous Pedal Design

Uses rod and crank system

Requires adjustment to

compensate clutch wear

Has 6 major high wear

surfaces

Mechanical geometry

(pivot points) limits

applications

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Bell Crank

Cable Clutch System

Non-Hydraulic

Clutch Linkage

Systems

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Hydraulic Clutch System Advantages

1. Easy to mount master

cylinder on flat surface

behind pedal (firewall)

2. Few wear items which

have much lower wear

than other clutch

linkage systems

3. Piston/Cylinderassemblies

automatically

compensate for clutch

surface wear and need

no adjustment

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Improved Design Goals

1. Make a system which allows

installation of hydraulic clutch

pedal when standard parts are

unavailable

2. Use mostly production or

aftermarket parts and keep custom

manufactured parts to a minimum

to be cost effective and practical

3. Use simple system that can be

implemented to any vehicles

firewall section (space permitting)

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Model Information

The improved pedal is a modified bell

crank unit retrofitted to operate a

Hydraulic Master Cylinder.

An actuation arm which joins the pedal

to the master cylinder rod is welded to

the original pedal.

The pedalhas a weight of 1.869 lb

(4.8359E-03 lbm).

Galvanized Annealed Steel is the

material used in the pedal.

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Material Properties for

Galvanized Annealed Steel

Modulus of Elasticity[psi] 2.7993E+07

Density [lbm/in^3] 7.5148E-04

Poisson's Ratio 0.2900

Thermal ExpansionCoefficient [ 1/degF ] 9.8889E-06

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Constrained and

loaded with 20 lb

applied load to lower

base pedal surface

Analyzed with Ansys

FEA Loads & Constraints

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Analysis Specifications

Applied Loads:

Type Entity X Y

Force [ lb ] Area 91.56 8.010 Force [ lb ] Area -14.14 -14.14

Reaction Forces [ lb ]:

X Y Z

-76.867 -22.103 -4.12794E-04

Total Moment [ lb-in ]:

X Y Z

7.4646 -85.318 98.502

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Equivalent Stress, Maximum

Principal Stress and Critical Point

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Fatigue Test

The Critical Stress (SC) on the clutch pedalis24.750 ksi.

108

Cycle Strength (endurance limit):Sn =Sn' * CL * CG * CS Sn' = 0.5*SU

= 25.48125 ksi. SU = 151 ksi

CL = 1

CG = 0.75

CS = 0.4

Since SC < Sn fatigue life is infinite.

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Corrosion & Wear Analysis

Pedal surfaces are painted

Every frictional surface is lightly greased and

insulated with a plastic bushing so anodiccorrosion of the material is irrelevant.

Rod is in contact with the pedal, which gives wayto adhesive wear.

Wear: W= KHFS K=10-3

= 5.0744*10-8 in.3 H= 452.832*103 psi.

= 8.3154*10-4 mm.3 F = 91.9134 lb.

S = 0.25 in.

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Disposal

Pedal assembly will

most likely be

salvaged at end ofvehicles useful life or

recycled with the rest

of the vehicle