. The engine speed was governed such that the vehicle normally could not exceed in third gear. The M18 carried a five-man crew, consisting of a commander, gunner, loader, driver, and assistant driver. The driver and assistant driver were seated in the front left and right of the hull, respectively. Uniquely, the driver and assistant driver were provided with identical sets of controls and either could be used to operate the vehicle, but only the driver's set of steering levers could be used as parking brakes. The commander, gunner, and loader were positioned in the turret; the commander at the left rear, the gunner at the left front, and the loader on the right. The commander, gunner, and loader were all provided with seats, and the commander could stand on his seat to operate the .50 caliber M2 Browning machine gun on a flexible ring mount on the left rear of the turret. An SCR-610 radio was placed in the rear of the turret. An escape hatch was provided in the hull floor directly underneath the turret. Armament In contrast to the M10 and M36 tank destroyers, which used the heavy chassis of the M4 Sherman, the M18 Hellcat was designed from the start to be a fast tank destroyer. As a result, it was smaller, lighter, more comfortable, and significantly faster, while carrying the same gun as the Sherman 76 mm models. The turret could rotate through 360 degrees in 24 seconds using an electro-hydraulic traverse mechanism, and the 76 mm gun could depress 10 degrees, and elevate 20 degrees. The maximum firing rate was 20 rounds per minute. The breech block of the gun was tilted 45 degrees to the right to aid the gunner in manipulating and inserting ammunition in the confined space of the turret. 45 rounds of main gun ammunition were carried, 9 in the turret to the right of the gun, and 18 in each sponson. A .50 caliber M2 Browning machine gun with 800 rounds of ammunition was mounted on the left rear of the turret in a flexible ring mount. Each crew member was provided with an M1 carbine with 90 rounds for self-defense, and six Mk 2 grenades, six M50 white phosphorus smoke grenades, and six smoke pots were also carried in the vehicle. One disadvantage of the M18 was the inconsistent performance of its 76 mm gun against the thick