Christie's pendant is an independent mechanism with a coil spring. The American designer John Christie invented this design. The main purpose of the device is to equip the tracked and wheeled tanks of the original configuration. In terms of dynamics, the new unit proved to be profitable in comparison with the traditional spring counterpart. This made it possible to increase the speed of movement of equipment over rough terrain with a lower profile. The first use of candle pendants was introduced on the M-1928 tank, with further development in all projects of the engineer until his death in 1944. Consider the features of this mechanism.
History of creation
Christie created a unique suspension for military high-speed armored vehicles with a significant power reserve. The tanks were intended to break through the enemy’s defensive line, eliminate their material and technical facilities, and disrupt the functioning of the rear cover and infrastructure. In the Soviet Union, such vehicles were classified as wheeled and tracked tanks.
The first developments of the designer were not very adapted for movement over rough terrain due to the limited capabilities of the suspension unit. In the second half of the 20s of the last century, the scientist spent a lot of time on modernizing the design and searching for innovative solutions. The main problem at that time was the presence of a large vertical spring size. To ensure a 250 mm spring travel, up to 700 mm of free space was needed to accommodate the struts and springs. This decision did not fit into the configuration of light armored vehicles.
Improvement
Christie's suspension has undergone yet another modernization in the form of using an L-shaped lever with a crankshaft. With his help, it was possible to change the movement of the spring from a vertical position to horizontal movement. The roller is fixed on one edge of the crank arm, moving exclusively vertically. The bend of the element is fixed to the body part, the second end of the part aggregates with the suspension spring, which is located horizontally inside the body.
The length of the spring mechanism is pretty decent. It provides a suspension unit stroke of 250 to 600 millimeters, depending on the modification of the equipment. John Walter Christie sold his invention to Britain and the USSR. Despite the fact that the tank suffered certain injuries during the jump, the suspension was purchased taking into account its further modernization.
Mover
Another interesting feature developed by an American engineer is the ability to change the chassis configuration. To move along the highway, it was enough to simply remove the tracks and drive exclusively on skating rinks. This made it possible to improve a number of parameters, namely:
- Increase the speed parameters of technology.
- Increase the range of the tank.
- To reduce the wear of the tracks, which at that time were quite fragile.
Christie's pendant aggregates with large-sized rollers that are coated with rubber protection. The diameter of the elements is equal to the height of the tracks, while the design does not use return rollers. The caterpillar tracks were equipped with a central guide ridge, the parts were paired, and a central guide ridge passed between the twin elements.
It is permissible to move around the rinks if the weight of the tank does not exceed certain parameters (20 tons). With increased values, the mass of equipment exerts significant pressure on the soil, which leads to its deformation. For example, when moving a convoy of cars of the type in question, they leave a deep track on the pavement, this especially affects the road surface in the heat. In the further development of tanks of this type, designers stopped on the development of only tracked vehicles (A-32, T-34).
Christie's Pendant: How It Works
The use of a thick rubber coating on the rim of the rink creates a certain bandage, which later went into the classic design of most light tanks. This solution can significantly extend the service life of the trucks. Due to the lack of polymers in wartime, the T-34 was produced with all-steel rollers, which the crews did not like because of poor operation.
A similar technique was subjected to significant vibration, which was transmitted to the hull, creating an unpleasant sound inside the tank. In addition, excessive vibration led to damage to military equipment, weakened the attachment of components and structural elements. Subsequently, the T-34 began to be produced, whose Christie suspension was equipped with a rubber rim on the first and fifth rink. In 1943, all-metal variations were completely discontinued. Additional vibration leveling was provided by internal shock absorption. This design is widely used on heavy armored combat vehicles.
Modifications
Christie’s tank suspension was actively used on Soviet military high-speed vehicles such as BT-2, BT-7, BT-5, T-34. On the latest model, the design in question was used most often. The node system included a vertically fixed spring of a spiral configuration placed at a small angle with respect to the housing.
Considering that enlarged rollers and a sagging track are the main features of the system under consideration, analogues with a torsion group are sometimes mistakenly ranked as models that use Christie's suspension.
The following are modifications of military vehicles that really used this type of suspension:
- BT-2/7/5, T-34, T-29 (Soviet defense industry).
- MK, Crusader, Comet, Charioteer (UK).
- Experimental variations of Italian- made tanks .
- Mk-1, Mk-4 (Israel).
- Japanese car in experimental performance (Ke-Ni).
Advantages and disadvantages
Candle suspension with a spring mechanism has a lot of advantages, which are mentioned above. However, this mechanism also has a number of disadvantages. These include the following points:
- Creating longitudinal vibrations that make it difficult to aim fire at full speed.
- Spring shafts significantly limited internal net volume.
- Sockets for balancers reduced the armor stability of the car body along the sides.
Further development
The considered type of independent suspension in the Soviet Union has been actively studied since 1940. This question was raised due to the need to modernize the popular T-34 tank. In the autumn of the same year, the Defense Committee adopted a decree in which it obliged the design bureaus and engineering departments under control to provide rationalization on the transition to the production of T-34 tanks using new technology. The design provided for an updated chassis with torsion bar suspension.
The development of documentation was entrusted to the design bureau of plant No. 183. The new project involved the use of existing rollers and balancing mechanisms. At the same time, the usable working volume increased by almost 20 percent, which made it possible to increase the fuel supply to 750 liters. This tank was located in the transmission compartment. To the advantages of such a solution should be added a decrease in the mass of the suspension itself by a total of almost 0.4 tons.
The outbreak of World War II significantly pushed innovative developments back. As a result, a new and improved torsion bar suspension on the T-34 and T-44 tanks appeared fully only in the late 40s of the last century.
Interesting Facts
The British Army acquired a Christie suspension tank (M-1936) equipped with telescopic hydraulic shock absorbers. This allowed us to get rid of the propensity of technology in terms of longitudinal vibrations of the body. At the same time, smoothness increased significantly. A similar unit was used on Israeli Merkava tanks (70s of the last century). It is still in active use.
The constituent parts of the device in question:
- Basic skating rink.
- Steering wheel.
- Skating rink for support.
- Caterpillar tape.
- Truckee.
- Track tensioner.
Finally
Candle pendant, or Christie's pendant, was a real breakthrough in equipping light military equipment. After some improvements, this design was actively used even on heavy tanks. A feature of the mechanism is the possibility of redistributing the load depending on the obstacles and soil to be overcome. In general, this design took root mainly on tanks of English, Japanese, American and Soviet production.