1 Basic Rail Vehicle Suspension Parameters

Presented by: Gary Wolf

Wolf Railway Consulting 2838 Washington Street Avondale Estates, Georgia 30002 404‐600‐2300 www.wolfrailway.com

Insert logo here in first Master slide Rail Vehicle Suspension Agenda 2 • 3 Primary Suspension Modes – Lateral, vertical, yaw/warp • Freight Cars – Springs and dampers – Yaw mode and truck warp • Passenger/Transit Cars – Springs and dampers – Lateral suspensions • Locomotives

Insert logo here in first Master slide 3 Primary Role of Suspension

• 1. Absorb vertical and lateral road shocks from perturbations in the track. Springs are used to slow down the over time, and store the . • 2. Dissipate the energy stored in the springs to prevent it from amplifying the motions of the road shocks and returning the energy back to the car. Dampers are used to dissipate the energy.

Insert logo here in first Master slide Energy Storage in a Spring 4

Insert logo here in first Master slide 5 Typical Motion Response of an Undamped Spring Displacement

Velocity

Acceleration

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Motion Response of a Damped Spring

Insert logo here in first Master slide 7 Vehicle Suspension Elements ‐ 3 Principal Modes

• Vertical Suspension • Lateral Suspension • Yaw/Warp Suspension

Insert logo here in first Master slide 8 Vertical Suspension

• Freight Cars – Secondary suspension springs between truck frame and bolster – Friction snubbers between frame and bolster – No Primary suspension • Passenger/Transit Cars – Primary suspension between wheelset and frame – Secondary suspension between frame and bolster, or frame and body • Locomotives – Primary and secondary elements

Insert logo here in first Master slide 9 Major Bodies Freight Cars

Car Body Truck Frame Truck Bolster Secondary Suspension Damper Secondary Suspension Springs

No Primary Suspension

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Spring: An Energy Storage Device

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Damper: Dissipates Energy

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Springs and Dampers Working in Parallel

Insert logo here in first Master slide 13 Major Bodies Passenger Car Body Vehicles

Secondary suspension supports carbody Bolster - swivels on truck

Truck frame - holds wheels in place

Primary suspension - lets wheel sets move up/down in frame

Insert logo here in first Master slide 14 Major Bodies Passenger Vehicles Car Body

Bolster Secondary suspension supports carbody

Truck frame - holds wheels in place

Primary suspension - lets wheel sets move up/down in frame

Insert logo here in first Master slide The Standard 3‐Piece Truck: 15 A long history of design improvements

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Bolster and Sideframe Interface Area

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Insert logo here in first Master slide 21 Nominal Wedge Position above top of Bolster

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Wear occurs on these 4 surfaces

Insert logo here in first Master slide Wedge rise above top of bolster due to wear 23

Insert logo here in first Master slide AAR Rule 46 (2007) 24

• Developed to address both friction casting front face wear, and total friction casting rise above top of bolster. Rules applicable when: – At any time of inspection – When car is on repair track • Rule 46 also addresses gib wear, centerbowl clearance, and column plate wear

Insert logo here in first Master slide Common Friction Casting 25 (Wedge) Designs

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Worn Out Friction Castings (Wedges)

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> 1 13/16” (~1 ¾”) Condemnable Per Rule 46

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> ¾” Generally Condemnable Per Rule 46 (Check Rule for exceptions!)

Insert logo here in first Master slide Barber Variable Damped Trucks ‐ Allowable Wedge Rise AAR Rule 46 29

Be Careful!!

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787-C Wedge ½” Wedge Rise

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Ride Control Gage

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ID

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Insert logo here in first Master slide Spring Groupings 34

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Count Springs; Verify Type; Verify Inner and Outer Springs; Check Free Height

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AAR Designated Spring Groups

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Right Side

Left Side; Missing corner inner coils

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Spring showing sign of fatigue/set

Insert logo here in first Master slide 40 Checking Free Height

Insert logo here in first Master slide 41 Broken Spring

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Solid Spring – Indicates Excessive Rock/Roll

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Truck Frame Swing Hanger Bushings Primary Suspension Pedestal

Tie Rod Bolster

Side Bearings

Secondary Suspension Equalizer Spring Plank General Passenger Swing Hanger Truck Components

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LOAD PATH

Secondary Suspension Truck Bolster

Frame Primary Suspension Equalizer

Spring Plank Basic GSI 70 Suspension

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Equalizer Springs Primary Suspension Truck Frame

Equalizer Bar

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Secondary Suspension Spring Plank

Equalizer Springs Primary Suspension Insert logo here in first Master slide 47 Air Spring Secondary Suspension Between Bolster and Car Body

Insert logo here in first Master slide Amfleet Passenger Car Trucks 48

Primary suspension at each journal

Shock Ring

Insert logo here in first Master slide Light Rail Vehicle Suspension 49 Air Spring Secondary Suspension Between Bolster and Frame

Note: vertical damper

Primary suspension at each journal

Insert logo here in first Master slide 50 Amtrak Superliner Car

Wagon Union Truck

Insert logo here in first Master slide Amtrak Superliner Car 51

Primary Suspension

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Secondary Suspension

Insert logo here in first Master slide 53 Locomotive Suspensions

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Primary Suspension

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Secondary Suspension

Insert logo here in first Master slide 56 Genesis Trucks

Insert logo here in first Master slide 57 Dampers

• Mostly hydraulic or friction style used on passenger cars • Used to absorb lateral and vertical shocks from track • Dissipates Energy from spring suspension • Restores ride quality

Courtesy Koni Company

Insert logo here in first Master slide Hydraulic Dampers ‐ 58 Construction

Courtesy Koni Company

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Typical Transit Car Vertical Suspension Showing Hydraulic Damper in Parallel with Air Spring

Insert logo here in first Master slide 60 Friction Dampers

Courtesy Vibratech Company

Insert logo here in first Master slide 61 Dampers ‐ Inspection Items

Insert logo here in first Master slide 62 Lateral Suspension

Insert logo here in first Master slide 63 Lateral Suspension

• 3‐Piece trucks have relatively poor lateral suspension characteristics, relying primarily on shear stiffness of load springs and friction due to wedge motion • Passenger/locomotive trucks have improved lateral suspension relying on both swing motion of the bolsters, shear of the secondary springs, and bump stops. In addition, lateral shock dampers are used.

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Bolster & Lateral Bump Stops

1” Nominal Bolster Stop to Body clearance; +1/4”, -0” tolerance

Lateral Bump Stops

Insert logo here in first Master slide Lateral Damper Air Spring 65

Side Bearing

Lateral Secondary Suspension Elements of Typical Transit Car

Showing Damper and Air Spring.Insert logo here in first Master slide 66 Yaw/Warp Suspension

Warp Stiffness Sideframe to Bolster

Warp/Yaw Stiffness Wheelset to Sideframe

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Warp Stiffness Sideframe to Bolster

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Warp/Yaw Stiffness Wheelset to Sideframe

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• Yaw/Warp Stiffness influences two primary responses – Hunting (high speed stability) – Truck Warp (Curving) • Freight Cars depend on the friction wedge system for warp stiffness • Passenger cars are normally rigid frame possessing high warp stiffness, but typically possess lower yaw stiffness

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90 Degrees Truck Hunting Lateral Instability

Wedges Help to Keep Truck Square

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Hunting of a Tapered (Conical) Wheelset

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Insert logo here in first Master slide Truck Hunting 73 Truck Stable Bolster Sideframe Remains Square Out of Square

Friction wedges Friction wedges worn provide squaring providing no squaring force

Insert logo here in first Master slide Hunting Speed Response 74 Hunting Severity Critical Speed for Hunting Prone Cars BH, ET, EF, EG

Lateral Critical Speed for G’s Most Cars

Speed MPH

10 20 30 40 50 60 70 80 Insert logo here in first Master slide 75

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Ideally, a truck should remain “Square” during curving to allow radial alignment of wheelsets with curve

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Insert logo here in first Master slide 80 Barber Frame Brace Truck

Frame Bracing increases the warp stiffness of the truck improving both high speed stability and curving.

Insert logo here in first Master slide 81 The End

Truck Suspension Basics

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