It’s easy for truck-fleet guys to lose track of how odd, or even maybe
obtuse some of the lingo involved in the trade can be. Whether you work on
them, drive them or buy them, there is a lot of stuff for the newcomers to
dice-up and swallow. And we need the newcomers. Times are such that recruitment
into any aspect of the trade has never been harder, so if I ever find anyone
with an innate love of equipment I try to encourage them… We need new folks in
the industry.
Because of that need, this installment can’t weight (intentional
misspelling), so let’s talk about your truck’s BMI. Or, what exactly do all
those weight-related TLA’s (three letter acronyms) mean, anyway? OK, full
disclosure: we graduated into FLA’s some time ago.
Billing terms-
·
Tare Weight: this is what the truck and its associated trailer (if
any) weigh before you put any product (payload) on it.
·
Gross Weight: this is the combined weights of the truck, trailer
and payload.
·
Net Weight: This is the result of subtracting the tare-weight from
the gross weight. IE: If you are hauling a bulk commodity, this is the product
you deliver.
·
Bill of Lading: Think of this as the truck’s ship-manifest. It
defines to any questioning authority what was hauled, and what time, on what
day.
So – Figure you are commissioning or operating a dump-truck to
haul some gravel to a job site. The truck will weigh at the scales on the way
into the quarry (establishing the tare weight) and weigh again on the trip out
(establishing the gross weight). The difference between these two numbers is
the Net Weight, or the amount of product you are hauling or paying for. Disclosure
of this weight and product description would go on the bill of lading. Pretty
straight-forward except for the medieval terms, right?
Equipment terms-
·
Payload: A somewhat vague word that is often thrown out by the
manufacturer when they are talking about the “Net Weight” capacity of a truck; often
seen in light-truck ads. I say somewhat vague because there are so many
variables that steer this, and it is by no means a fixed number. Remember, fuel
weighs in at 6¼-7lbs/gal, depending on what flavor you are burning, and
passengers and the driver figure in too. So dependent on your tank level and
how many McDoubles you or your co-pilot wolfed-down before you got on the road,
this number can move… A lot.
·
GAWR – Gross Axle Weight Rating: this is the maximum amount of
weight that can be placed on any specific axle, and the figure results from the
weakest of the spring ratings, tire ratings or mechanical axle ratings. So why
wouldn’t you want to match all these values you ask? Good question. Stability
or safety margin. IE: I will often spring a vocational truck with a 21K lb.
rear axle with 23.8k lb. springs. This can stiffen up the roll-resistance on
units that load-out top heavy, making for a more confident feeling truck.
·
GVWR – Gross Vehicle Weight rating: this is the maximum weight
that the power unit (truck only) can roll at. This is governed by the interplay
of GAWR’s, frame strength, spring ratings, driveline configuration and stopping
capabilities.
·
GCWR – Gross Combined Weight Rating. This is probably the one that
matters most in trucking. This is a rating of how much the truck can weigh and
pull at the same time. This figure takes in to account power/torque, gear
ratios, transmission type and the resulting gradeabity (the trucks ability to
hold speed on a climb), as well as the ability to stop the thing once it’s
rolling.
OK – We’ve addressed this weighty topic, so we’ll do another next
time. Stay away from multiple McDoubles!
© 2018 D.W. Williams
