Fleet Maintenance - 30

SPOTLIGHT ON UNDER VEHICLE

The
RIGHT
FIT

The history and
importance of the
spiral steel bushing.

By Drake Piper and Alejandro Ayala

t's what's on the inside that counts."
The adage is seemingly as old as time, but what
we don't always hear is the story of how we got
"what's on the inside." In the trucking industry,
so many moving parts come together to power
a safe and productive fleet, and they all need to
fit together. Arguably, nowhere is the fit more
important than with the steer axle kingpin kit.
Drake Piper, sales manager for Kaiser, GAFF
and Equipment, and Alejandro Ayala, senior
product manager for Kaiser Products, both
from Stemco, talk about why kingpin kits
are so important, what to look for, and how
to maintain them. They also explain how
one of today's most popular bushings -
the spiral steel bushing - came to be
and why the industry didn't accept
it right away.

30 Fleet Maintenance | July 2020

What are kingpins and what purpose
do they serve on commercial trucks?
What kinds of kingpin kits are there?
Alejandro Ayala: The main role of a kingpin is
to maintain the steering geometry of the alignment of the truck. It is a combined bearing system
that supports the loads of the axle and allows the
steering of the vehicle. In today's market, there
are several options for kingpin kits. The main
component that most shops think about when
determining which kit to purchase is the bushing
type included in the kit. There are many different
kingpin kits on the market including nylon, bronze,
bi-metal, composite, and the spiral steel bushing.
Specifically, what is the spiral steel
bushing and how is it unique?
Ayala: This component in the kit is key for the
durability of a kingpin repair. The softer the material, or if the materials are not proper for the loads,
the more prone the components are to reduced life
and repeated repairs, adding maintenance costs.
This can lead to higher fuel costs, downtime, and
excessive wear on tires. This is where the spiral
steel bushing shines: in providing low cost-permile for fleets.
What is the story behind
the development of the
spiral steel bushing?
Drake Piper: Back in the 1960s, Kaiser was a
company making spiral steel bushings [which were
used as drill press bushings] for
the "Big Three" [automakers] in
the Detroit area. There was a
milkman who was

»The main role of a kingpin is to maintain the
steering geometry of the alignment of the truck.
95491131 | bucky_za | Getty Images

having a lot of problems with his kingpins on his
milk truck. He stopped in [to Kaiser] and said, "I
need some help." And that's where [his] inventive
mind came into play, saying, "Can this steel bushing be used as a kingpin bushing?"
The updated bushing design for kingpins was
adapted, worked, and later presented to a fleet
called Consolidated Freightways [who installed
the spiral steel bushings] on its vehicles. After six
months, they said, "These things work great, they
grease great, and they last a lot longer."
How was the product received
in the industry? How did the
perception change over time?
Why do you think it changed?
Piper: For the first 25 or 30 years, [the spiral steel
bushing] was primarily used on school buses,
the Consolidated Freightways fleet vehicles, and
a few other vehicles around the country. It was
something so different. It was metal on metal; the
thought was that it would ruin the spindle.
Ayala: As we worked to expand usage, customers were reluctant to try the bushing, thinking
that since it was a steel bushing, it would weld
and ruin the axle.
Piper: However, as customers came around and
gave it a try, they found that the Kaiser spiral steel
bushing lasted longer - a lot longer than a normal
kingpin kit. In fact, they lasted about four times
longer than kits without a
spiral steel bushing. The
»For a kingpin kit,
the quality of the
components also adds
a lot of value to
the durability
of the kit.
Images from Stemco

Fleet Maintenance

Table of Contents for the Digital Edition of Fleet Maintenance