Churchill Mk VII during field trials
The Churchill tank had several unique features related to its mobility that set it apart from other tanks of its time, though it also reflected some of the challenges Britain faced in tank design.
Engine and Power
The lack of suitable engines was a significant issue for British tanks. The Churchill used a 21.3-liter, 350-horsepower twin-six engine. This engine was developed by Vauxhall Motors in only 89 days and was a horizontally opposed, side-valve design to fit the limited space in the tank’s hull. Although not the most powerful engine, it enabled the Churchill to meet its mobility requirements, which emphasized heavy armor and trench-crossing ability over speed.
Transmission Layout
The gearbox and final drive were at the rear of the tank behind the engine, which gave the Churchill a lower silhouette than American tanks, which had these components at the front. This design choice minimized the need for a bulky transmission tunnel and allowed for a more compact fighting compartment. However, it also complicated maintenance and repair.
Tracks and Suspension
The tracks were designed with trench warfare in mind, and the tank featured long, wide tracks to cross large obstacles and reduce ground pressure. The Churchill’s tracks initially used pressed steel plates but were upgraded to cast links over time to improve durability. The suspension system was complex, with 11 individually mounted roadwheels supported by a unique coil spring arrangement. This setup gave the Churchill exceptional climbing ability and allowed it to traverse deep mud and rough terrain, where other tanks might get bogged down.
Cross-Country Mobility
Although slow – reaching a maximum speed of 15.5 mph on roads and only 8 mph off-road – the Churchill excelled in difficult environments. Its low ground pressure and high angle of track contact made it especially useful in rough terrains like the mountains of Tunisia and Italy, as well as the deep mud of the Reichswald during the later stages of World War II. Its neutral steering capability allowed the Churchill to make sharp turns in tight spaces, such as on Italian mountain roads.
Driving Challenges
Operating the Churchill required significant skill. It had a four-speed crash gearbox that was difficult to handle, and steering was controlled by handlebars, using a Merritt-Browne regenerative steering system. This allowed for neutral turns, a valuable feature for navigating difficult terrain. However, the driver’s visibility was limited, particularly to the sides, where the protruding track horns blocked the view. Drivers often had to rely on their periscopes and the commander’s directions during combat, as the visor was typically closed for protection.
Despite its slow speed, the Churchill’s robust design and mobility in challenging conditions made it one of the most reliable tanks for infantry support, especially in environments where other tanks struggled.