The Road, Indoors, Held to ±0.05 km/h.
Every drive cycle a lab runs — an emissions test, an EV range determination, a hot-country durability schedule — assumes one thing above everything else: that the machine under the wheels behaves indistinguishably from real tarmac. Neometrix's chassis dynamometer is that machine. It replaces the road with rollers and then spends every millisecond making the substitution undetectable — 4×4 with four independently driven wheels, to 250 km/h, inertia simulation across 150–5,500 kg, and four-quadrant drives that absorb regenerative braking so it tests EVs as honestly as it tests combustion engines.
The Road Is an Equation the Dyno Must Obey
A coastdown test on a real road yields a vehicle's road-load: F = A + B·v + C·v² — a constant term, a speed term, and an aerodynamic square term. The dynamometer applies that exact force at every speed, continuously, to a road-load accuracy of about ±1 kgf at the roll surface. Get that equation wrong and every test the vehicle runs afterward is measuring the dyno, not the vehicle.
Most of the Vehicle's Mass Isn't in the Room
The rolls themselves carry a base mechanical inertia of about 1,360 kg per axle. Everything between that figure and the vehicle actually being simulated — anywhere across a 150–5,500 kg envelope — is created electrically by the drives, in 0.454 kg steps. That only works if the control loop answers in under 65 milliseconds; slower than that, and a gearshift feels like a software glitch instead of real mass responding.
Four Quadrants, Because Vehicles Push Back
Overrun, downhill schedules and EV regenerative braking all drive power into the machine rather than drawing it out. Four AC flux-vector motor-absorbers, each around 224 kW, work across all four quadrants — absorbing power under normal load, and motoring the vehicle when the cycle demands it. That's what makes a single machine honest for testing both combustion engines and EVs, rather than requiring separate rigs for each.
Also Offered as an Upgrade
The same underlying engineering modernises existing chassis dynamometers already in service — new drives and controls, load cells, centering-device overhaul, calibration and full acceptance testing — without touching the existing civil pit. Indian test facilities are specifically asking for exactly this kind of upgrade path, and it's carried as a defined scope of supply, not an afterthought retrofit.
Sized to the Vehicles and the Standard
Roll diameter, installed power, inertia envelope and cell integration all follow from the vehicle classes being tested and the drive cycles being run. The reference configuration here — 4×4, 48-inch rolls, 250 km/h, roughly 900 kW installed — was engineered against India's current vehicle-laboratory build-out. No order followed this specific configuration, so no specific delivered dynamometer is claimed on this page.
Frequently Asked Questions
Why does a chassis dynamometer need to simulate the vehicle's mass electrically instead of just using a heavy enough roller?
Because the range of vehicle masses a single dynamometer needs to test — anywhere from about 150 kg to 5,500 kg in the referenced configuration — is far too wide to cover with physical flywheels alone, and physical inertia can't be adjusted precisely or quickly between different test vehicles. Instead, the rolls carry a fixed base mechanical inertia (roughly 1,360 kg per axle), and everything beyond that is created electrically by the drive motors, adjustable in small steps (0.454 kg) to match whatever vehicle is being tested. This only works if the control loop responds fast enough — under 65 milliseconds — that the electrical simulation feels instantaneous rather than lagging behind the real vehicle's dynamics.
Why do EVs need a different kind of chassis dynamometer than combustion-engine vehicles?
Because EVs push energy back into the system during regenerative braking, which a traditional dynamometer designed only to absorb power (like a simple brake) can't handle safely or accurately. A four-quadrant dynamometer, using AC flux-vector motor-absorbers, can both absorb power from the vehicle under normal driving and motor the rolls to push power back to the vehicle when needed — for example simulating going downhill. That four-quadrant capability is what lets the same physical machine test combustion engines and EVs equally honestly, rather than requiring a combustion-only dyno for one and a separate EV-specific rig for the other.
Get In Touch
For full specifications, RFQs, or a technical discussion about the chassis dynamometer:
- Product page: Chassis Dynamometer
- Email: contact@neometrixgroup.com
- Phone: +91-7777-876-876
Top comments (0)