Balancing Central Stock Against Truck Stock

Why this matters

Every part you own sits in one of two places: close to the work on a truck, or held back at the shop. How you split the same total stock between those two tiers decides two things you feel every day, whether a tech can finish a job without a supply run, and whether you can see and control what you own. Push too much onto the trucks and you have paid to duplicate the same slow parts across the whole fleet. Hold too much back and your techs burn billable hours driving to restock. The balance is the whole game.

Two tiers, two jobs

Think of it as one inventory living at two speeds.

• Truck stock is the fast tier. Parts already in the tech's hands. Its job is speed: finish the common call on the first trip, no return, no wait. It is expensive per slot because every slot is multiplied by the number of trucks.
• Central stock is the deep tier. The shop shelf that holds the range you cannot justify on every truck, feeds the trucks as they draw down, and absorbs the bulk buys and the occasional parts. Its job is coverage and control: one place to count, one place to reorder, one place the whole fleet draws from.

You are not choosing between them. You are deciding how much of each part lives on which tier, and the answer differs by part.

The two failure modes pull opposite ways

A parts operation goes wrong in one of two directions, and they have opposite symptoms.

• Over-centralized. Trucks run lean, so techs hit the shop or the supplier mid-day, again and again. The tell is a fleet that spends its morning driving to parts instead of to jobs. Every supply run is billable time spent, a stalled customer, and a callback risk. Cheap on paper, brutal on the clock.
• Over-distributed. Every truck carries a wide range just in case. The tell is bloated trucks, the same slow part sitting on many trucks at once, and no one able to say what the fleet holds. You have frozen cash across the fleet and lost the single count that lets you control it.

Name which way you are drifting. The fix for one is the poison for the other.

Standardize the truck, vary the shop

The single biggest lever is a standard truck list: one defined load-out that every truck of the same type carries, set from your real call mix, not from each tech's habits.

• A standard list makes trucks interchangeable, auditable, and restockable to a known target. You can tell at a glance what is short.
• It kills the private-hoard problem, where every truck is stocked differently and none can be checked.
• It lets the shop hold the variety. The truck carries the predictable bread-and-butter; the shop carries the range that backs it up.

Vary the standard list by truck role (a service van and an install rig need different loads) and by season, but keep it a defined list, not a free-for-all.

The flow between the tiers

Balance is not a one-time split. It is a flow: central feeds the trucks, suppliers feed central.

• Trucks replenish to par from the shop, not from the supplier. The tech draws down during the day; the restock routine tops each truck back to its standard list from shop stock. This keeps the supplier relationship at one tier instead of every tech ordering.
• The shop replenishes from suppliers on reorder points, sized to lead time and the draw from all trucks combined. See related: Setting Reorder Points So You Never Run Out Mid-Job.
• Usage logged at the job is what drives both. If parts leave the truck without being recorded, the flow runs blind and both tiers drift.

Let fleet size and geography set the dial

There is no universal split. Two facts move it.

• Fleet size. With one or two trucks, the truck and the shop nearly merge, so push more onto the truck, since duplication is cheap. As the fleet grows, every part on the standard list is multiplied by the truck count, so the cost of a wide truck load-out climbs fast and the case for a deep central shelf strengthens.
• Distance and drive time. Techs working far from the shop need fuller trucks, because a supply run costs an hour or more of billable time. Techs working tight to the shop can run leaner and lean on the deep tier.

Set the dial to your own numbers: a big fleet working far out standardizes a fuller truck and holds real depth centrally; a small fleet working close can run lean trucks off a modest shop shelf.

References

• See related: Stock a Part on the Truck or Order It Per Job Decision Tree, The Truck Stock That Earns Its Space
• See related: The Truck-Restock Routine That Keeps Crews Moving, Setting Reorder Points So You Never Run Out Mid-Job
• U.S. Small Business Administration (SBA), inventory and working-capital management guidance
• Trade-standard practice for multi-tier parts stocking and standard truck load-outs