Glossary
Truck repair glossary
All pages in this section
GVWR (Gross Vehicle Weight Rating)
What GVWR means, how it determines whether a truck is a commercial motor vehicle under 49 CFR 390.5, and why repair shops record it.
How to Check a Truck VIN for Open Recalls (NHTSA)
A recall check uses a vehicle VIN to look up open safety recalls in the NHTSA database. How repair shops use it and what it does not show.
PM Service (Preventive Maintenance)
What a PM service is for trucks and trailers, how PM schedules are set, and how preventive maintenance connects to 49 CFR 396.3 records.
Tire Tread Depth Rules for Trucks (4/32 and 2/32)
Federal minimum tread depth for commercial vehicles: 4/32 inch on steering axle tires of a power unit and 2/32 inch on other tires. Where the rules come from.
VIN (Vehicle Identification Number)
What a VIN is under 49 CFR Part 565, why it matters for truck and trailer repair, and how shops use it on work orders, inspections, and recalls.
VMRS Codes (Vehicle Maintenance Reporting Standards)
What VMRS codes are, how the system, assembly, and component code keys work, and why fleets ask repair shops to code invoices with VMRS.
What Are ATA Codes in Truck Maintenance?
ATA codes are the American Trucking Associations maintenance coding system, now known as VMRS, used to classify truck repairs by system, assembly and component.
What Are Billable Hours in a Repair Shop?
Billable hours are the labor hours a repair shop charges to customers on repair lines. How they differ from clocked hours and why they drive shop revenue.
What Are Engine Hours?
Engine hours measure how long an engine has run. Why shops record engine hours alongside mileage and how they drive PM intervals for trucks, reefers and equipment.
What Are Hours of Service (HOS) Rules?
Hours of service rules limit how long truck drivers may drive and work. Learn the 11-hour, 14-hour, 30-minute and 60/70-hour limits in 49 CFR 395.3.
What Are Net Terms?
Net terms are invoice payment terms that give a customer a set number of days to pay the full amount, such as net 15, net 30 or net 60.
What Are the 3 Cs
The 3 Cs (complaint, cause, correction) are the standard way to document each repair line so customers, fleets and warranty reviewers understand the work.
What Are the Out-of-Service Criteria?
The North American Standard Out-of-Service Criteria are the CVSA pass-fail standards used at roadside inspections. How they relate to 49 CFR 396 and shops.
What Does Net 30 Mean on a Repair Invoice?
Net 30 means the full invoice amount is due 30 days after the invoice date. How net 30 terms work for truck repair shops and fleet customers.
What Happens When a Truck Fails an Inspection?
An inspection failure means a truck or trailer did not meet the inspection standard. What it means for annual inspections, roadside inspections and the repair shop.
What Is 49 CFR 396?
49 CFR Part 396 is the federal rule on inspection, repair and maintenance of commercial motor vehicles. A plain summary of each section for shops.
What Is a Brake Chamber?
A brake chamber turns air pressure into the pushrod force that applies a truck's air brakes. Learn the types, sizes and the stroke limits in 49 CFR 393.47.
What Is a Brake Inspector (49 CFR 396.25)?
A brake inspector under 49 CFR 396.25 is anyone responsible for commercial vehicle brake inspection, maintenance, service or repair. The qualification rules.
What Is a Card Hold?
A card hold reserves funds on a customer's card without charging it yet. How mobile repair shops use card holds before rolling to a road call, and what to know about expiry.
What Is a CDL (Commercial Driver's License)?
A CDL is the license required to drive certain large or hazardous commercial vehicles. Learn the Group A, B and C classes defined in 49 CFR 383.5.
What Is a Comeback in Truck Repair?
A comeback is a vehicle that returns to the shop for the same problem after a repair, usually redone at no charge. Causes, costs and how shops track them.
What Is a Core Charge?
A core charge is a refundable deposit on a part that can be remanufactured, refunded when the old part comes back. How shops should handle and bill it.
What Is a Core Return?
A core return is sending the old, rebuildable part back to the supplier to get the core charge credited. How core returns work in a truck repair shop.
What Is a Crane Truck?
A crane truck, or mechanic truck with a crane, is a service truck with a mounted crane for lifting heavy components such as tires, transmissions and engine parts in the field.
What Is a DOT Annual Inspection?
The DOT annual inspection is the periodic inspection required by 49 CFR 396.17. What it covers, who can do it, and what records it needs.
What Is a DVIR (Driver Vehicle Inspection Report)?
A DVIR is the written report a commercial driver prepares on vehicle defects under 49 CFR 396.11. What it covers, who certifies repairs, and how long it is kept.
What Is a Fleet Maintenance Contract?
A fleet maintenance contract is an agreement between a fleet and a repair shop covering what maintenance and repair the shop does, at what rates, and on what terms. What it usually includes.
What Is a Labor Guide?
A labor guide is a reference that lists standard labor times for repair operations on specific vehicles and components, used for estimates and flat-rate billing.
What Is a Labor Rate?
A labor rate is the price per hour a repair shop charges for technician time. How shops set it, how it shows up on invoices and how it differs from the effective labor rate.
What Is a Mileage Charge for Mobile Repair?
A mileage charge is a per-mile fee a mobile mechanic adds for travel to the job, usually beyond a set distance or service area.
What Is a Mobile Service Truck?
A mobile service truck is a truck equipped with tools, air, power, parts and often a crane so a technician can repair trucks and equipment on site.
What Is a Parts Line on a Repair Invoice?
A parts line is the invoice or work order line that lists one part supplied, with its description, part number, quantity and price.
What Is a PM A Service?
A PM A service is the lightest, most frequent level of preventive maintenance in a tiered truck PM program, usually a lube, oil and filter service with a basic inspection.
What Is a PM B Service?
A PM B service is the middle level of a tiered truck preventive maintenance program, adding more inspection and service items to the PM A list.
What Is a PM C Service?
A PM C service is the most complete level in a tiered truck preventive maintenance program, usually done least often and covering major fluids, components and a full inspection.
What Is a Post-Trip Inspection?
A post-trip inspection is the end-of-day vehicle check that feeds the DVIR under 49 CFR 396.11. What it covers and how shops handle the defects it finds.
What Is a Pre-Trip Inspection?
A pre-trip inspection is the check a commercial driver makes before driving under 49 CFR 392.7 and 396.13. What it covers and what it means for shops.
What Is a Preventive Maintenance Interval?
A preventive maintenance interval is the mileage, engine hours or time between scheduled services on a truck or piece of equipment.
What Is a Purchase Order in a Repair Shop?
A purchase order is a document that authorizes a purchase. Repair shops use two kinds: POs they send to parts suppliers and PO numbers fleets give them to approve work.
What Is a Qualified Inspector (49 CFR 396.19)?
A qualified inspector is a person allowed to perform DOT annual inspections under 49 CFR 396.19. The criteria and the records carriers keep.
What Is a Repair Order (RO) in a Truck Repair Shop?
A repair order is the shop document that authorizes, tracks and records the work done on a vehicle, from the customer concern to the final parts and labor.
What Is a Road Call in Truck Repair?
A road call is a service call where a technician goes to a broken-down truck or trailer, usually on the road or at a customer site, to repair it.
What Is a Service Call Fee?
A service call fee is a flat charge a mobile mechanic or field service business adds for coming to the customer, covering travel and setup before any repair labor.
What Is a Slack Adjuster?
A slack adjuster links the brake chamber pushrod to the camshaft on air drum brakes and keeps brake stroke in limits. Federal requirements and shop checks.
What Is a Special Order Part?
A special order part is a part a repair shop does not stock and orders for one specific job or customer. How shops handle deposits, returns and approvals.
What Is a Unit Number?
A unit number is the fleet's own identifier for a truck, trailer or piece of equipment, used on repair orders, invoices and maintenance records.
What Is a Work Order in Truck Repair?
A work order is the document that defines and tracks a repair or maintenance job, assigning the work to technicians and recording parts, labor and results.
What Is Accounts Receivable Aging?
Accounts receivable aging groups unpaid invoices by how long they have been outstanding, so a repair shop can see who owes what and follow up on late payments.
What Is an After-Hours Rate?
An after-hours rate is a higher labor rate or added fee a repair business charges for work outside regular hours, such as nights, weekends and holidays.
What Is an Air Brake on a Truck?
An air brake system uses compressed air to apply the service, parking and emergency brakes on heavy trucks, trailers and buses. Learn the parts and the rules.
What Is an ELD (Electronic Logging Device)?
An ELD records a commercial driver's duty status automatically. Learn the federal ELD rule, the December 18, 2017 deadline and what it means for shops.
What Is Book Time?
Book time is the standard number of labor hours a labor guide or the shop assigns to a repair, used to price flat-rate jobs and to measure technician efficiency.
What Is CVSA (Commercial Vehicle Safety Alliance)?
CVSA is the nonprofit of commercial vehicle safety officials and industry that publishes the out-of-service criteria and inspection decals. What it means for shops.
What Is Days Sales Outstanding (DSO)?
Days sales outstanding (DSO) measures the average number of days it takes a business to collect payment after a sale. How repair shops calculate and use it.
What Is Effective Labor Rate (ELR)?
Effective labor rate is total labor sales divided by labor hours billed. How to calculate it for a heavy-duty repair shop and why it differs from your posted rate.
What Is Emergency Roadside Repair for Trucks?
Emergency roadside repair is unplanned repair done where a truck broke down, to get it safely moving or ready to tow. How it works and what affects the price.
What Is Estimate Approval in Truck Repair?
Estimate approval is the customer's recorded authorization of a repair estimate before work begins, including who approved, when, and for what amount.
What Is Field Service in Truck and Equipment Repair?
Field service means repair and maintenance done at the customer location, such as a fleet yard, job site or roadside, rather than in the repair shop.
What Is Field Service Management (FSM)?
Field service management is how a business schedules, dispatches and tracks technicians who work at the customer's location. What it means for mobile diesel and heavy-equipment repair.
What Is Flat Rate in a Repair Shop?
Flat rate means charging or paying a set number of labor hours for a job regardless of the time it actually takes. How it works for heavy-duty shops.
What Is FMCSA (Federal Motor Carrier Safety Administration)?
FMCSA is the U.S. DOT agency that regulates commercial motor vehicle safety, including the inspection and maintenance rules in 49 CFR Part 396.
What Is Parts Markup?
Parts markup is the amount a repair shop adds to its cost for a part to set the selling price. Markup versus margin, examples and how shops set it.
What Is Shop Management Software?
Shop management software runs the work of a repair shop, from the first call to the paid invoice. What it covers for diesel, truck and heavy-equipment shops, and how to choose one.
What Is Statement Billing?
Statement billing sends a customer a periodic summary of all open invoices and payments, which helps fleets reconcile and pay many repair invoices at once.
What Is Technician Efficiency?
Technician efficiency compares the hours a technician produces, such as flat-rate or billed hours, with the hours actually worked on jobs. Formula, example and how to use it.
What Is Technician Productivity?
Technician productivity is the share of a technician's paid time spent working on jobs. Formula, example and how it differs from technician efficiency.
Why Do Repair Orders Record the Odometer Reading?
The odometer reading records vehicle mileage on a repair order. Why shops capture it, which rules require it, and how it supports PM schedules and warranty claims.
Questions
Where do the definitions come from?
Each entry lists its sources, most often the eCFR or the FMCSA.
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