axle design

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DESIGN OF AXLE FOR RIGID DUMP TRUCKS

AN OVERVIEWAbove 40 Ton Class

Content

• Snap Shot of Axel and Layout

• Overview of Axel Design

• Axel Specification

• Design Process

– Design Calculations

– Design of Components

• Example – Design of Axel Shaft

Snap Shot of Axel and Layout

RIGID DUMP TRUCK REAR AXLE

POWRTRAIN LAYOUT

Snap Shot of Axel and Layout

POWRTRAIN LAYOUT

Snap Shot of Axel and Layout

POWRTRAIN LAYOUT

Snap Shot of Axel and Layout

REAR VIEW

FRONT VIEW

Snap Shot of Axel and Layout

Manufacturing Drawings

Design Verification and Validation

Geometric Modeling of Axel

Axel Specification

Axel Type Load CapacityTorque

CapacityReduction

RatiosDifferential

SpecsBrake specs

Rim & Tire Specs

Wheel Tread

Axel Component Design

Differential Bevel Gears Planetary Gears Bearings Brakes Center Housing Axel Shafts

Torque Calculation

Prime-mover torque Slip torque from GVW

Vehicle Parameters

Engine Power Engine Torque Transmission Gear Ratio Tire Size

Overview of Axel Design

• Full-Floating Planetary AxelAxel Type

• Max Load • Max Torque

Axel Capacity

• Bevel Ratio • Final Drive Ratio• Total Ratio

Reduction Ratios

• Spiral Bevel Gear and Straight Bevel Gear Differential

Specification

• Oil Cooled Wet-multiple disk typeBrake Specification

• Rim Size• Tire Size• Wheel Tread

Tire Specification

Axel Specification

Following Vehicle Parameters considered

– Engine output power

– Engine output torque

– Transmission Gear Ratio• First Gear - For gradability

determination

• Top Gear – For top speed determination

– Selection of tire size

Design Process

• Torque Calculation

Input torque to axel is determined by calculating Prime-mover torque and Slip torque due to GVW, smaller of the both is considered as input torque to axel

Prime-mover torque

Slip Torque due to GVW

Design Process

• Design of Differential

– Type :

• Plug-in differential, conventional type

• Spiral and Straight Bevel Gears

Design Process

DIFFERENTIAL ASSEMBLY

Design Process

• Design of Bevel Gears

– Design methodology published by American Gear Manufacturing Association (AGMA)

– Gear teeth primarily designed for two factors• Resistance to pitting caused by contact stresses

• Bending strength capacity based on cantilever beam theory

– Material processing:• Heat treatment

– Convert weaker grain structures to stronger ones

• Tempering

– Relieve brittleness and internal strains prior to machining

• Carburization

– Adds high hardness and strength at surface and toughens core to withstand impact stress

Design Process

• Design of Bevel Gears

• Torque application to a bevel gear induces tangential, radial, and separating loads assumed to act as point loads applied at the mid-point of the gear tooth

• Reaction loads are a result of the tapered roller bearings that support the gear shaft and counteract the gear loads

• Loads are primarily a function of torque, pitch diameter, pitch angle, pressure angle, and face width

• Loads and bending moments are calculated based on a vectoral combination of two planes

Design Process

• Deign of Planetary Gears– Calculation of final drive ratio, No. of teeth, pressure angle, contact

ratio, tip diameter, tip width, root diameter, radial clearance, inspection parameters

– Calculation of gear bending and contact strengths

Design Process

• Bearing Life Calculation

– L10 Bearing life

– Speed and Load on Axel

– Duty cycle of usage

Design Process

• Design of Brake System

– Type : Wet-Multiple Disk Brakes

– Features :

• Effective cooling due to higher heat transfer rate

• Self adjustable disks

• Sealed – Free from dust & contamination

• Oil Cooled

• Retarder

Design Process

• Design of Brake System– Calculation of brake capacity

• Actual capacity

• As per SAE Standard

• As per ISO 3450

Basis of calculation

» Load on Axel – GVW

» Wheel Base

» Center of Gravity

» Gradability

» Loaded Radius

Design Process

• Design of Brake System

– Sizing of Brake

• Determining disk diameter

• Co-efficient of friction between disks

• Actuation pressure

• Disk area

• No. of disks

• FOS

Design Process

• Design of Central Housing

– Features :• 3 piece construction

• Steel casting

• Ease of manufacturing

Design Process

• Design of Axel Shaft

– Full floating axel shaft, no load on axel shaft

– Only torsional load

– Stress is calculated for

• Shear stress at body

• Compressive & shear Stress at spline

– Stress at bolted joints is calculated considering,

• Tensile stress developed due to clamping force

• External applied load

Design Process

Merritt Innovative Solutions India Private Limited

# 131/2, 1st Floor, West Of Chord Rd, 11th

Cross, 2nd Stage, Mahalakshmipuram,

Bangalore-86.

info@merritt.in

+91 80 23196515 / 516