Christie's pendant, or candle pendant: description, application, features

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

Christie's Suspension is an independent mechanism with a helical coil spring. This design was invented by American designer John Christie. The main purpose of the device is to equip tracked and wheeled tanks of the original configuration. In terms of dynamics, the new unit proved to be advantageous 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 a candle suspension was introduced on the M-1928 tank, with further development in all the engineer's projects until his death in 1944. Consider the features of this mechanism.

History of Creation

Christy created a unique suspension for combat high-speed armored vehicles with a significant power reserve. The tanks were intended to break through the enemy's defensive line, eliminate its material and technical facilities, disrupt the functioning of the rear cover and infrastructure. In the Soviet Union, such vehicles were classified as wheeled-tracked tanks.

The first developments of the designer were not very suitable for moving over rough terrain due to the limited capabilities of the nodependants. In the second half of the 20s of the last century, the scientist spent a lot of time modernizing the design and searching for innovative solutions. The main problem at that time was the presence of a large vertical size of the spring. To provide 250mm of spring travel, up to 700mm of free space was needed to accommodate the struts and springs. Such a decision did not fit into the configuration of light armored vehicles.

Improvement

Christie's suspension has undergone another upgrade in the form of an L-arm with a crankshaft. With its help, it was possible to change the movement of the spring from a vertical position to a horizontal movement. The roller is fixed at one end of the crank arm, which moves exclusively vertically. The bend of the element is fixed on 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 suspension unit travel from 250 to 600 millimeters, depending on the modification of the equipment. John W alter Christie sold his invention to Great Britain and the USSR. Despite the fact that the tank received some damage during the jump, the suspension was purchased taking into account its further modernization.

Motor

Another interesting feature developed by an American engineer is the ability to change the chassis configuration. To move along the highway, it was enough just to take off the trucks and drive exclusively onskating rinks. This made it possible to improve a number of parameters, namely:

• Increase vehicle speed.
• Increase tank movement range.
• Reduce wear and tear on tracks that were quite fragile at the time.

Christy's suspension aggregates with large rollers that are covered with rubber protection. The diameter of the elements is equal to the height of the tracks, while the design does not use return type rollers. The tracks were equipped with a central guide ridge, the parts were produced in pairs, and a central guide ridge passed between the twin elements.

It is permissible to move on skating 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 ground, which leads to its deformation. For example, when a column of cars of the type in question moves, they leave a deep rut on the asph alt, which especially negatively affects the road surface in the heat. In the further development of tanks of this type, the designers settled on the development of only tracked specimens (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 entered the classic design of most light tanks. This solution allows to significantly extend the service life of the tracks. Due to the lack of polymers in wartime, the T-34s were produced with all-steel rollers, which were very disliked by combat crews due topoor operation.

This technique was subjected to significant vibration, which was transmitted to the hull, creating an unpleasant sound inside the tank. In addition, excessive vibration caused damage to combat equipment, weakened the fastening of nodes and structural elements. Subsequently, the T-34 began to be produced, the Christie suspension of which was equipped with a rubber rim on the first and fifth rollers. In 1943, all-metal variations were completely discontinued. Additional leveling of vibration was provided by internal shock absorption. This design has found wide application on heavy armored fighting vehicles.

Modifications

The suspension of the Christie tank was actively used on Soviet high-speed combat vehicles such as BT-2, BT-7, BT-5, T-34. On the latest model, the design in question was used most often. The assembly system included a vertically fixed spring of a spiral configuration, placed at a slight angle with respect to the body.

Given that oversized rollers and a sagging track are the main features of the system under consideration, analogues with a torsion group are sometimes mistakenly classified as models using Christie's suspension.

The following are modifications of combat vehicles that actually 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 experimental car (Ke-Ni).

Pros and cons

Candle suspension with a spring mechanism has a lot of advantages, as mentioned above. However, this mechanism also has a number of disadvantages. These include the following points:

• Creating longitudinal oscillations that make it difficult to conduct aimed fire at full speed.
• Spring shafts significantly limited the internal usable volume.
• Nests for balancers reduced the armor stability of the vehicle hull on the sides.

Further development

The considered type of independent suspension in the Soviet Union has been actively studied since 1940. This issue was raised because of the need to modernize the popular T-34 tank. In the autumn of the same year, the Defense Committee adopted a resolution in which it ordered the design bureaus and engineering units under its control to provide a rationalization on the transition to the manufacture of T-34 tanks using the new technology. The design provided for an updated chassis with a torsion bar suspension.

The development of the documentation was entrusted to the design bureau of plant No. 183. The new project provided for the use of existing rollers and balancing mechanisms. At the same time, the useful 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, one should add a reduction in the mass of thependants in general almost 0.4 t.

The beginning of the Second World War significantly pushed back innovative developments. As a result, a new and improved torsion bar suspension on the T-34 and T-44 tanks appeared fully only at the end of the 40s of the last century.

Interesting facts

The British Army purchased a tank with a Christie suspension (M-1936) equipped with telescopic hydraulic shock absorbers. This made it possible to get rid of the tendency of technology in terms of longitudinal vibrations of the hull. At the same time, the smoothness of the ride has significantly increased. A similar knot was used on Israeli Merkava tanks (70s of the last century). It is still actively exploited.

Component parts of the device in question:

• Track roller.
• Guide wheel.
• Rink for support.
• Crawler belt.
• Tracks.
• Track tensioner.

In closing

The candle pendant, or Christie's pendant, has become a real breakthrough in equipping light military equipment. After certain modifications, this design was actively used even on heavy tanks. The peculiarity of the mechanism lies in the possibility of redistributing the load depending on the obstacles to be overcome and the ground. In general, this design has taken root mainly on tanks of English, Japanese, American and Soviet production.