March/April 2024 - 28

Vehicle design
wheel versus ultra-resilient wheel) has
very little effect on average vibration for
a vehicle already equipped with a soft
primary suspension.
" But even in this case, the resilient
wheel is still very important for noise
control, despite the lesser impact on
ground vibrations, as it provides more
benefit at higher frequencies, " Perez said.
Car builders also use multibody simulations
to model carbody connection
types, truck steering configurations and
solid axles versus independently rotating
wheels. This performance is typically
expressed in vibration and noise, truck
lateral force values and wheel squeal propensity,
respectively.
According to Perez, both models and
field tests have shown that independently
rotating wheels meet the excitation
threshold associated with wheel squeal
more frequently than solid-axles under
a wide variety of operating conditions.
" Although independently rotating
wheels don't have a profound effect on the lower frequency
range affecting ground vibrations, they have a very clear impact
on higher frequencies affecting noise generation, " Perez said.
These simulations and data from field testing have helped
Stadler develop general internal guidelines for optimized
truck designs:
* A soft primary suspension is the main vehicle parameter influencing
ground vibrations, followed by a low unsprung mass.
* Ultra-resilient wheels are only justified when combined with
stiff primary suspension.
* Friction-free carbody connections produce lower vibration
and noise than alternatives.
* Optimized primary suspension steering systems and solid
axles provide the best performance in terms of truck lateral
forces and noise generation.
Guidelines like these are valuable, especially when backed
by simulation and field data. On top of these design considerations,
car builders must consider vehicle/track interactions
unique to the customer and their operating environment. By
incorporating track data into their modeling and simulations,
car builders can tailor their design to the true track condition
rather than the design spec and ensure that even in the
worst-case scenario, the vehicle will meet performance and
safety specifications.
Part 2 of this article
will continue to
follow the discussion
on vehicle design,
held at the 2023
Wheel/Rail Transit
Conference and
will take a closer
look at some of the
ways in which car
builders collect and
integrate track data
and the importance
of taking a holistic
approach to vehicle/
track interaction.
About the author
Jeff Tuzik is managing
editor of Interface
Journal.
For more information, visit www.MassTransitmag.com/21252748
2402MASS_Wheel Rail Seminars.indd 1
28 Mass Transit | MARCH/APRIL 2024
1/26/24 4:02 PM
http://www.MassTransitmag.com/21252748

March/April 2024

Table of Contents for the Digital Edition of March/April 2024

Urban mobility’s hands-free future is near
People & Places
Special Report: Bus Fleet Snapshot
TriMet’s Powell Garage leads way in modern transit facilities
Park City investment in driver subsidized housing is a win-win
Vehicle Design: Managing Wheel/ Rail-Generated Noise and Vibration from the Ground Up
The Transportation Technology Center: A Hub for Advanced Passenger Train Testing
Products
March/April 2024 - 1
March/April 2024 - 2
March/April 2024 - 3
March/April 2024 - 4
March/April 2024 - 5
March/April 2024 - Urban mobility’s hands-free future is near
March/April 2024 - 7
March/April 2024 - People & Places
March/April 2024 - 9
March/April 2024 - 10
March/April 2024 - 11
March/April 2024 - Special Report: Bus Fleet Snapshot
March/April 2024 - 13
March/April 2024 - 14
March/April 2024 - 15
March/April 2024 - TriMet’s Powell Garage leads way in modern transit facilities
March/April 2024 - 17
March/April 2024 - 18
March/April 2024 - 19
March/April 2024 - Park City investment in driver subsidized housing is a win-win
March/April 2024 - 21
March/April 2024 - 22
March/April 2024 - 23
March/April 2024 - Vehicle Design: Managing Wheel/ Rail-Generated Noise and Vibration from the Ground Up
March/April 2024 - 25
March/April 2024 - 26
March/April 2024 - 27
March/April 2024 - 28
March/April 2024 - 29
March/April 2024 - The Transportation Technology Center: A Hub for Advanced Passenger Train Testing
March/April 2024 - 31
March/April 2024 - 32
March/April 2024 - 33
March/April 2024 - Products
March/April 2024 - 35
March/April 2024 - 36
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