Every drive cycle a lab runs \u2014 an emissions test, an EV range determination, a hot-country durability schedule \u2014 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 \u2014 4\u00d74 with four independently driven wheels, to 250 km\/h, inertia simulation across 150\u20135,500 kg, and four-quadrant drives that absorb regenerative braking so it tests EVs as honestly as it tests combustion engines.<\/p>\n
A coastdown test on a real road yields a vehicle’s road-load: F = A + B\u00b7v + C\u00b7v\u00b2 \u2014 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 \u00b11 kgf at the roll surface. Get that equation wrong and every test the vehicle runs afterward is measuring the dyno, not the vehicle.<\/p>\n
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 \u2014 anywhere across a 150\u20135,500 kg envelope \u2014 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.<\/p>\n
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 \u2014 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.<\/p>\n
The same underlying engineering modernises existing chassis dynamometers already in service \u2014 new drives and controls, load cells, centering-device overhaul, calibration and full acceptance testing \u2014 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.<\/p>\n
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 \u2014 4\u00d74, 48-inch rolls, 250 km\/h, roughly 900 kW installed \u2014 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.<\/p>\n