NMX‑DTR‑30 / Rev 00 / driveline & powertrain test / spectrum · torsion · endurance 2026 · Product Page

NMX-DTR-30 · ENGINEERED TO ORDER — DRIVELINE TEST RIGS FOR TRACKED & WHEELED HEAVY VEHICLES

Torque is easy to apply. It is the least of what breaks a driveline.

Name: Heavy Vehicle Driveline Test Rigs
Brand: Neometrix

A steady torque figure proves almost nothing. What destroys transmissions and torsion bars is the spectrum — reversals, shock steps and the resonances that live between the engine and the ground. Which is why the hardest requirement on a driveline rig is negative: it must add no dynamics of its own. Flywheels, couplings and shafting give a rig natural frequencies too, and one inside the test band makes the rig fail the part — or worse, sit somewhere flattering and pass one it should have failed. Two things follow. A torsion bar is rated by what it absorbs, not what it holds, so the test is angle-controlled, cycle-counted, and measured at the article. And absorption is regenerative, because a rig that turns full power into heat pays for every kilowatt twice for a decade. Equipment of this class has been quoted across transmission, torsion-bar and road-wheel test rig requirements for heavy vehicle drivelines; no delivered driveline test rig is claimed — the class is engineered to order.

Enquire — driveline test rig Capability sheet (PDF)

Illustrative of the class — a heavy vehicle transmission test rig on a long fabricated steel bedplate with machined T-slots: a large mid-grey electric drive machine on a bolted pedestal, a bright machined coupling inside an open guard, a heavy grey cast gearbox mounted in a bolted steel cradle as the article under test, a cylindrical in-line torque transducer on its own bearing pedestal and a second identical electric machine acting as the load at the far end, with cable trunking running to a plain control cabinet with a completely blank door, no people, nothing running and no readable markings

Fig · 01 Drive at one end, load at the other — and the whole difficulty is everything the rig adds in between

Loads by

a spectrumnot a torque figure

Designed around

its own resonanceskept out of the band

Measures

angle at the articlenot at the drive

Absorbs

regenerativelythe bill runs for years

Status

engineered to orderquoted class

ISO 9001 / 14001 Engineered to order Driveline & powertrain test Correlation & commissioning Noida · India

Overview

The rig has to make a road it can never drive on.

Everything difficult about this class comes from that — and from the fact that the rig is itself a driveline, with opinions of its own.

Illustrative of the class — a torsion bar test rig: a long slender solid steel bar mounted horizontally between two heavy grey fixed steel end housings bolted to a machined bedplate with its splined ends clamped in bright machined adapters, a mid-grey hydraulic rotary actuator applying twist through a short lever arm at the near end, a slim cylindrical rotary encoder on a bright bracket reading angle directly at the article, and stainless hydraulic tubing running to the actuator, no people, nothing running and no readable markings

Fig · 02 The encoder sits at the bar, not at the actuator — the difference between a measurement and a flattering one

Start with what actually wears a driveline out. A heavy vehicle driveline rarely dies of a single overload; it dies of accumulation. Every gear change, every track shock through the final drive, every reversal from drive to overrun puts a cycle into gear teeth, splines, bearings and shafts, and the component fails when enough of them have gone by. So the useful test is not "apply the rated torque and see" — that is a proof test, and a driveline that fails it was already broken. The useful test is to replay the duty: the sequence of loads, reversals and shocks the vehicle really delivers, compressed into something a laboratory can run in months rather than years. Which means the rig's real specification is not a peak number but a spectrum it can reproduce faithfully.

Then confront the awkward fact. The rig is itself a rotating driveline — drive machine, couplings, shafting, flywheels, load machine — and it therefore has its own inertia and its own torsional natural frequencies. Those are not a nuisance to be ignored; they are part of the experiment. Put one inside the band of excitation and the rig amplifies what it was only supposed to apply: the article now sees loads the vehicle never produces, and fails a test it should have passed. The subtler and more dangerous case is the opposite — a resonance that lands somewhere convenient can absorb energy the article should have taken, and a marginal component sails through. Neither outcome announces itself in the data, which is why the torsional model is designed with the article, and why the assembled rig is characterised before the first test piece is fitted.

And measure where the truth is. On a torsion bar rig especially, angle read at the actuator includes every degree of wind-up in the rig's own shafting — so the bar looks softer than it is, and its permanent-set limit arrives later than it really does. The encoder belongs at the article.

Equipment of this class has been quoted across transmission, torsion-bar and road-wheel test rig requirements for heavy vehicle drivelines. No delivered driveline test rig is claimed: the class is engineered to order, and the record is stated as it stands.

Duty

A spectrum, replayed

Reversals and shock steps — not a number the rig can reach.

Honesty

No dynamics of its own

Resonances placed outside the band — and proven there.

Economics

Power put back

Four-quadrant regeneration — heat costs twice, for a decade.

Architecture

Load the spectrum, add nothing of your own, and put the power back.

The schematic follows the argument — why a torque figure is not a duty, and how a rig's own resonances corrupt the answer — then the four blocks behind it.

FIG · 03DRIVELINE RIG ARCHITECTURE · DRIVE + ABSORPTION / TORSIONAL DESIGN / MOUNTING + REACTION / MEASUREMENT, CONTROL + SAFETY

Fig · 03 The detail worth reading twice — why a torsion bar is rated by what it absorbs

Arc · 01

Drive & Absorption

Four-quadrant load, regenerated — commanded torque held in both directions, smoothly, straight through a reversal.

Arc · 02

Torsional Design

Inertia sized to the vehicle — shafting stiffness and couplings chosen to place resonances outside the band, then verified.

Arc · 03

Mounting & Reaction

Torque into a stiff foundation — adapters, alignment and guarding, so the building never joins the spring.

Arc · 04

Measurement, Control & Safety

Angle at the article — torque, speed, temperature, spectrum playback, cycle counting and abort logic fast enough to matter.

Specifying a driveline rig, or replacing one whose results nobody quite trusts? Send the article types and ratings, the duty cycle or spectrum, the test programme and the applicable standard — a clause-by-clause compliance matrix within two working days · [email protected]

Send tender spec

Specifications

Sized on the duty, judged on what the rig does not add.

The parameters below describe the engineering approach. Drive and absorption ratings, inertia and shafting design, fixturing and foundation interface, instrumentation and abort logic all follow from four givens: the articles and their ratings, the duty cycle or spectrum to be reproduced, the test programme, and the applicable standard.

Illustrative of the class — a road wheel endurance test rig: a large plain unmarked solid rubber-tyred road wheel held on a stub axle in a heavy mid-grey pivoting steel arm and pressed against the face of a much larger smooth steel drum, with a hydraulic cylinder above the arm applying radial load through a clevis, a load cell in line with it, a bare steel mesh guard around the contact and the drum's bearing pedestals bolted to a machined bedplate, no people, nothing running and no readable markings

Fig · 04 Running gear asks a different question — not how much it takes, but how long it lasts rolling

Where these rigs go wrong

Sized on peak torque, blind to the spectrum — the rig can reach the headline number and can never reproduce the duty that actually breaks things, so it certifies components that fail in service. A rig resonance inside the test band — the rig fails the part, and no one can prove afterwards which of the two was at fault. Angle measured at the drive rather than the article, so the rig's own wind-up is credited to the bar and every torsion bar reads softer than it is. Dissipative loading on a facility with a ten-year life — the electricity and the cooling plant quietly cost more than the rig, and that was a design decision made by omission. Fixturing that does not react torque cleanly, so the foundation joins the spring and the measured stiffness partly belongs to the building. And abort logic too slow — a driveline letting go at full torque with a loaded flywheel behind it destroys the fixture, and sometimes the rig.

So the discipline runs the other way. The duty is established as a spectrum before any rating is chosen, and the drive and absorption are sized to reproduce it rather than to reach a peak. The torsional model is designed with the article, resonances deliberately placed outside the excitation band, and the assembled rig characterised and its response measured before the first article is fitted. Angle is taken at the article, and rig compliance is characterised and subtracted rather than hoped away. Absorption is four-quadrant and regenerative as a default, because the running cost outlives the capital argument. Fixturing and foundation are designed as part of the instrument. And the abort chain is specified by how fast it acts, not by the fact that it exists.

Full specification — expand

System	Heavy vehicle driveline test rig — drive & absorption, torsional design, article mounting & fixturing, measurement, control & safety
Governing Idea	Torque is the easy part. What breaks drivelines is the spectrum — reversals, shock steps and the resonances between the engine and the ground
The Rig's Own Dynamics	Flywheels, couplings and shafting give the rig natural frequencies of its own. One inside the test band and the rig amplifies what it was only meant to apply
The Worse Failure	A resonance somewhere flattering absorbs energy the article should have taken — a marginal component passes, and nothing in the data says so
Torsional Design	Inertia sized to represent the vehicle's mass; shafting stiffness and couplings chosen to place resonances outside the band; the assembled rig characterised before the first article runs
Torsion Bars	Rated by what they absorb, not what they hold — an angle reached repeatedly without taking a permanent set. Angle-controlled, cycle-counted, judged on a trend: unload to free angle, measure, repeat, watch for drift
Where Angle Is Measured	At the article. Read at the drive, rig wind-up is credited to the bar and every bar reads softer than it is
Absorption	Four-quadrant, regenerative — commanded torque held in both directions through a reversal. Dissipative loading pays for every kilowatt twice and needs the cooling plant to match
Road Wheel & Running Gear	A different question: not how much it takes but how long it lasts rolling — a loaded wheel against a drum for millions of revolutions, heat build-up governing, and safe to leave running unattended
Fixturing	Torque reacted into a foundation stiff enough not to join the spring; adapters and alignment designed, guarding sized for stored rotational energy
Safety	Abort logic specified by how fast it acts — a driveline letting go at full torque with a loaded flywheel behind it destroys fixtures
The Split	The helicopter main gearbox load test rig tests an aviation gearbox, where mass is the enemy and a failure is catastrophic; here mass is free and the enemy is a duty cycle measured in thousands of hours of shock loading. The axle test rig with acoustic enclosure hunts noise, and is built quiet to hear it; this one hunts life, and is built stiff so as not to lie about it. And the dynamic turret test rig is the same class of vehicle, a different subsystem — slew and stabilisation rather than what puts the vehicle on the ground
Scope Boundary	Ours: rig design & integration, duty-cycle & spectrum definition, drive & four-quadrant absorption including regeneration, torsional design (inertia simulation, shafting, couplings, resonance placement and verification), article mounting, fixturing & torque reaction, the foundation interface, instrumentation with angle measured at the article, control, spectrum playback, cycle counting & abort logic, guarding, installation, commissioning, correlation, documentation, training, spares & AMC — including build to the customer's specification. Bought-in certified: drive and load machines and their converters, torque transducers, encoders, couplings and shafting, gearboxes, instruments and control hardware. The customer's: the test articles, the duty cycle, the applicable standard and the acceptance programme
Status	Engineered to order — equipment of this class quoted across transmission, torsion-bar and road-wheel test rig requirements for heavy vehicle drivelines; no delivered driveline test rig is claimed

PDF · 1 page

Heavy Vehicle Driveline Test Rigs — Capability Sheet

Tender Response

Send articles, ratings, duty cycle & programme — compliance matrix in two working days

Variants

One discipline, four rigs.

What changes is which part of the driveline is on the bedplate — and therefore what question the rig is being asked.

Var · 01

Transmission Test Rig

Full power, regenerative — spectrum playback through the gearbox, torque held cleanly through every reversal.

Var · 02

Torsion Bar Test Rig

Angle-controlled, cycle-counted — twist to a limit, unload, measure the set, and follow the trend.

Var · 03

Road Wheel & Running Gear Rig

Millions of revolutions against a drum — loaded endurance, heat build-up watched, safe to run unattended.

Var · 04

Final Drive & Reduction Gearbox Addition

The last stage before the ground — where shock from the track arrives first and reduction multiplies it.

Applications

Wherever a driveline has to be believed before it is put under a vehicle.

Development, qualification, overhaul acceptance and life extension.

A · 01Tracked vehicle drivelines

A · 02Wheeled heavy vehicle transmissions

A · 03Suspension torsion bars & springs

A · 04Final drives & reduction gearboxes

A · 05Running gear & road wheels

A · 06Overhaul acceptance & life extension

FAQ

Common questions.

Plain-language answers from the engineering team.

Q · 01 Why is a torque rating not a specification for a driveline rig?

Because a driveline almost never dies of one big load. Gear teeth, splines, bearings and shafts fail by accumulation: every gear change, every shock arriving through the final drive, every reversal from drive to overrun deposits a cycle, and the component gives up when enough of them have passed. A rig that can reach the rated torque and hold it steady is therefore testing the one condition least likely to be the cause of a failure — that is a proof test, and an article that fails a proof test was broken before it arrived. What matters is whether the rig can reproduce the duty: the amplitude distribution, the reversals, the shock steps and the rate at which they arrive, compressed so a laboratory can run in months what a vehicle takes years to accumulate. That is a much harder requirement, because it governs how quickly the drive and load machines can change torque, how faithfully the control loop follows a commanded profile, and how much of the commanded shape survives the rig's own mechanical response. So when we specify a rig, the duty cycle comes first and the ratings fall out of it — not the other way round.

Q · 02 What does it mean for a rig to "add dynamics of its own"?

A test rig for a rotating machine is itself a rotating machine. Drive machine, couplings, shafting, flywheels, the article, the load machine — all of it forms one torsional system with inertias connected by springs, and every such system has natural frequencies at which it will happily amplify a disturbance. That is unavoidable; what is avoidable is where those frequencies sit. If one falls inside the band the test excites — and a spectrum with reversals and shock steps excites a wide band — then the torque arriving at the article is no longer the torque commanded: the rig has added its own contribution, and the article is being asked to survive a machine rather than a vehicle. The obvious failure is the article breaking early, which at least announces itself, though it usually starts an argument nobody can settle. The dangerous failure is quieter: a resonance can also absorb energy at the wrong place, so the article sees less than intended and a marginal component passes. Nothing in the recorded data distinguishes that from a good component. This is why the torsional model belongs in the design phase alongside the article, why inertia is chosen to represent the vehicle rather than whatever flywheel is available, and why the assembled rig is characterised — measured, not calculated — before the first test piece is fitted.

Q · 03 Why must torsion bar angle be measured at the bar rather than at the actuator?

Because everything between the actuator and the bar twists too. A torsion bar on a tracked vehicle is the suspension spring: it is not rated by a torque figure but by the angle it can be twisted to, over and over, without taking a permanent set. So the whole test is an angle measurement, and its accuracy is the accuracy of the result. Read that angle at the actuator and you have measured the bar plus the adapters, the splined couplings, the fixture and the rig's own shafting — all of which contribute real degrees under load. The bar therefore appears softer than it is, and, worse, its apparent permanent set is contaminated by any settling elsewhere in the load path. The fix is not clever software: it is putting a rotary encoder on the bar's own clamped end, so the measurement spans the article and nothing else, and treating the fixture's own compliance as something to be characterised and subtracted rather than assumed negligible. The same logic sets the acceptance criterion: because a single reading cannot distinguish elastic deflection from the beginnings of a set, the rig unloads to free angle and re-measures at intervals, and the answer is the shape of the drift across thousands of cycles.

Q · 04 Why does regenerative loading matter so much on a rig like this?

Because of what a test programme costs to run, not what the rig costs to buy. A transmission rig works by driving the article at one end and absorbing at the other, and that absorbed power has to go somewhere. Dissipate it — in a water brake or a resistor bank — and the facility pays for every kilowatt twice: once drawn from the supply to put it in, and again in the cooling plant that removes it from the building, along with the water, the space and the maintenance that plant needs. On a rig running endurance programmes for years, that recurring cost comfortably exceeds the difference in capital between a dissipative and a regenerative design. A four-quadrant electrical load machine instead pushes the absorbed power back onto the site bus, where the drive machine promptly re-uses most of it; the supply then only has to make up the losses. The consequences reach beyond the electricity bill: the site connection and switchgear are sized for a fraction of the circulating power, the cooling plant shrinks dramatically, and the machine room becomes a far more pleasant place to work. There is a control benefit too — an electrical load machine holds commanded torque in both directions, including smoothly through a reversal, which a dissipative brake fundamentally cannot do, and reversals are exactly what the duty cycle is full of.

Q · 05 How is a road wheel rig different from the rest of the family?

It asks about life rather than strength, and that changes the machine. A transmission or torsion bar rig applies a load path through a shaft; a road wheel rig creates a rolling contact. The wheel is pressed against a large drum whose surface stands in for the ground, and then simply run — for millions of revolutions. Nothing is being proved about how much load the wheel can take; what is being found is where it stops being serviceable: the elastomer degrading, the bond to the rim failing, the bearing wearing out, or heat building up faster than it can escape. Three consequences follow. Heat is a governing parameter, not a nuisance: a rubber-tyred wheel dissipates real power into hysteresis, and running it faster to finish sooner changes the temperature and therefore the failure mode, so the duty has to be respected rather than accelerated for convenience. The rig must be safe to leave running, because programmes last weeks and no one will watch them: that means monitoring, defined abort behaviour and guarding sized for a wheel that may come apart. And the drum is part of the instrument — its diameter changes the contact patch geometry and therefore the answer, which is why it is specified deliberately rather than chosen from what fits in the bay.

Q · 06 What do you build, what is bought in — and what is claimed?

Divided honestly. What Neometrix provides: the rig design and integration — derived from the articles and the duty rather than from a catalogue; duty-cycle and spectrum definition, which is where the specification actually comes from; the drive and four-quadrant absorption scheme including regeneration; the torsional design — inertia simulation, shafting stiffness, coupling selection and the deliberate placement of resonances outside the test band, verified by characterising the assembled rig before the first article runs; article mounting, fixturing and torque reaction, including the foundation interface, so the building never becomes part of the spring; the instrumentation with angle measured at the article, control, spectrum playback, cycle counting and abort logic specified by how fast it acts; guarding for stored rotational energy; and installation, commissioning, correlation, documentation, training, spares and AMC — including build to the customer's own specification. What is bought-in certified: the drive and load machines and their converters, torque transducers, encoders, couplings and shafting, gearboxes, instruments and control hardware — proprietary products of established makers, integrated rather than imitated. What is the customer's: the test articles, the duty cycle, the applicable standard and the acceptance programme. And the record, stated plainly: equipment of this class has been quoted across transmission, torsion-bar and road-wheel test rig requirements for heavy vehicle drivelines, and no delivered driveline test rig is claimed. The class is engineered to order, around the duty it has to reproduce.

↗

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Browse all Neometrix product lines.

Get a quotation

Send the articles
and the duty they must survive.

The projects desk replies within two working days with a clause-by-clause compliance matrix and a budgetary quotation. Write to [email protected] or use the form.

Enquire — driveline test rig Capability sheet (PDF) +91 7777 876 876

ISO 9001 / 14001 ENGINEERED TO ORDER — HEAVY VEHICLE DRIVELINE TEST RIGS LOAD THE SPECTRUM · ADD NO DYNAMICS OF YOUR OWN · MEASURE AT THE ARTICLE ENGINEERED IN NOIDA · INDIA

Torque is easy to apply. It is the least of what breaks a driveline.

The rig has to make a road it can never drive on.

A spectrum, replayed

No dynamics of its own

Power put back

Load the spectrum, add nothing of your own, and put the power back.

Drive & Absorption

Torsional Design

Mounting & Reaction

Measurement, Control & Safety

Sized on the duty, judged on what the rig does not add.

Where these rigs go wrong

One discipline, four rigs.

Transmission Test Rig

Torsion Bar Test Rig

Road Wheel & Running Gear Rig

Final Drive & Reduction Gearbox Addition

Wherever a driveline has to be believed before it is put under a vehicle.

Common questions.

A gearbox that flies, an axle that must be quiet, and a turret that must not miss.

Helicopter Main Gearbox Load Test Rig

Axle Test Rig with Acoustic Enclosure

Dynamic Turret Test Rig

Send the articles
and the duty they must survive.

Similar Products

Share This Page

Torque is easy to apply. It is the least of what breaks a driveline.

The rig has to make a road it can never drive on.

A spectrum, replayed

No dynamics of its own

Power put back

Load the spectrum, add nothing of your own, and put the power back.

Drive & Absorption

Torsional Design

Mounting & Reaction

Measurement, Control & Safety

Sized on the duty, judged on what the rig does not add.

Where these rigs go wrong

One discipline, four rigs.

Transmission Test Rig

Torsion Bar Test Rig

Road Wheel & Running Gear Rig

Final Drive & Reduction Gearbox Addition

Wherever a driveline has to be believed before it is put under a vehicle.

Common questions.

A gearbox that flies, an axle that must be quiet, and a turret that must not miss.

Helicopter Main Gearbox Load Test Rig

Axle Test Rig with Acoustic Enclosure

Dynamic Turret Test Rig

Send the articlesand the duty they must survive.

Similar Products

Share This Page

Send the articles
and the duty they must survive.