Tons per Hour: Reading the Band Honestly

Tons per hour is the number buyers compare across suppliers and the number most often quoted without its conditions. This article is how to read a t/h figure honestly: what the band assumes, why suppliers quote ranges, and how to convert a t/h claim into the daily tonnage your operation will actually see. The reference machine is the Q91-500, whose published band is 45 to 60 tons per day.

What a t/h Figure Assumes

Every tons-per-hour figure carries four assumptions, and none of them is a machine property:

Material density. Tons per hour is a weight figure, and the weight per cut depends on what is in the box. Dense heavy sections and light loose scrap produce different tons from the same cycle rate — which is why the same machine quotes different t/h figures for different material.

Loading synchronization. The figure assumes the tank stays charged — the excavator or grapple keeps pace with the cycle rather than surging and starving it.

Discharge clearing. The figure assumes cut pieces leave the discharge zone at the rate the box delivers, with no banking up under the machine.

Running hours. The figure assumes the machine runs the hours counted, with the maintenance window deducted rather than ignored.

A supplier quoting a single t/h number is assuming all four at their ideal. A supplier quoting a band is telling you the range your operation will land in depending on how the four are managed — and the band is the honest version.

Why We Quote Ranges

The published bands exist because the four assumptions are operational, and the operation differs yard by yard. The Q91-500’s 45 to 60 tons per day is a real range: a yard with sorted demolition feed, a dedicated grapple and a discharge arrangement that clears lands at the top; a yard with mixed unsorted intake and a shared excavator lands at the bottom. The machine is the same; the operation is not.

This is why the quotation conversation is about your material list and your loading equipment rather than about the t/h figure. The number that matters is not what the machine can do but what your yard will make it do — and the class guide covers the material the band assumes.

Converting t/h Into Your Daily Tonnage

The conversion is the arithmetic the strokes-versus-tons guide covers in full, and the short version is:

1. Take the cycle rate and multiply by your tons per cut — from your material mix, weighed if possible.
2. Apply the loading factor — realistically 0.7 to 0.85, depending on how well your excavator keeps the tank charged.
3. Apply the discharge factor — a deduction if your handling cannot clear at the box’s rate.
4. Deduct the maintenance window — daily checks, weekly gap measurements and blade rotations, in hours per week.

The result is your shift’s tonnage, and it should land inside the published band. If it lands above, you are planning to run at the ceiling; if below, check whether the deductions are honest or whether the class is oversized for your operation.

The Two Failure Modes

Planning at the ceiling. The buyer who computes from the headline figure and plans the operation at the theoretical maximum discovers the gap in month one — and blames the machine. The gap is the four assumptions, and it was visible before the order.

Sizing from the bottom. The buyer who reads the bottom of the band as the machine’s limit and sizes down a class. The band’s bottom assumes the worst version of all four assumptions; a yard that manages them well lands at the top, and the right class is the one the honest computation supports.

The Band as a Specification Conversation

The honest use of a t/h figure is as the start of a conversation rather than the end of one. Send your material mix, your loading equipment, your discharge arrangement and your shift pattern — and the written quotation comes back within two business days confirming the class whose band your operation will actually land in. If the honest answer is the class below the one you asked about, the quotation will say so: a machine whose band your operation cannot reach is paying for capability it cannot spend, every shift.

The Assumption Audit

The four assumptions behind any t/h figure can be audited against your own operation in an afternoon, and the audit is what converts a supplier’s number into your number. Material density: weigh a week’s output if you can, estimate from the mix if you cannot. Loading synchronization: watch the excavator for a shift and count the minutes the tank spends empty. Discharge clearing: watch the discharge zone at the busiest hour and count the minutes material banks up. Running hours: count the hours the machine actually runs, with the maintenance window deducted rather than ignored.

The audit produces four factors, and the factors applied to the cycle rate produce your tonnage. It is the same arithmetic the strokes guide covers, and it is the only version of the t/h figure that describes your operation.

The Band as Filter

The published bands are also a filter for suppliers, and the filter works in one direction: a figure well outside a class’s published band needs its assumptions stated. A 200-ton machine quoting 100 tons a day is quoting a number the class’s architecture cannot deliver — either the counting method differs or the brochure does. Ours publishes the bands because they are what the machines actually do, and a supplier that cannot state its assumptions is describing a search term rather than a machine.

Use the bands as the first question in any comparison: what does this figure assume, and does my operation have what it assumes? The answer is either a specification conversation or a deflection, and both are useful before the deposit.

The Band, Priced

The band prices the machine against your operation, and the pricing is the audit. Each of the four assumptions has a cost when it fails: material density that differs from the assumption moves the tons per cut; loading that starves the tank moves the loading factor; discharge that cannot clear moves the discharge factor; running hours that shrink move the window. A band quoted against assumptions your operation does not meet is a number your operation will not reach — and the gap prices as the tonnage difference times the margin, every shift.

The audit converts the supplier’s band into your number, and your number is what the class decision should be made against. The computation guide covers the five steps, and the range table is the reference the audit checks against.

The Audit as the Conversion

The four-part audit converts a supplier’s band into your number, and your number is what the class decision should be made against. The audit takes an afternoon and it replaces assumption with observation: weigh the output, watch the excavator, watch the discharge, count the running hours. Four observations, four factors, and the tonnage your operation actually produces.

Run the audit before the order and the band becomes a specification rather than a promise. The computation guide covers the five steps, and the range table is what the result checks against.

Buyer FAQ

Why do suppliers quote t/h as a range?

Because the figure assumes material density, loading synchronization, discharge clearing and running hours — all operational rather than mechanical. The band is the honest version of a number that moves with the operation.

What is the biggest variable in the band?

Material density and loading rhythm. Dense sorted feed with a dedicated grapple lands at the top; mixed unsorted intake with a shared excavator lands at the bottom — same machine, different operation.

How do I convert t/h into my daily tonnage?

Cycle rate times tons per cut, then apply the loading and discharge factors and deduct the maintenance window. The result should land inside the published band for that class.

What if my computation lands above the band?

You are planning at the ceiling, which is where blade life and cycle time go to die. Either the class is oversized or the assumptions need a second look.

Is a higher t/h figure always a better machine?

Only if your operation can reach it. A band your yard cannot reach is capability you are paying for every shift — the honest class is the one whose band your material and loading equipment will actually fill. Run the four-part audit in an afternoon and convert the supplier’s band into your number — the audit is the only version of the t/h figure that describes your operation, and it is what the class decision should be made against. Run the four-part audit in an afternoon and convert the supplier’s band into your number — the audit replaces assumption with observation, and your number is what the class decision should be made against. The audit takes an afternoon and it replaces assumption with observation — weigh the output, watch the excavator, watch the discharge, count the running hours, and the four factors produce your tonnage.