helicopter Transmission
helicopter Transmission

helicopter Transmission


Transmission helicopter - a set of structural elements (units) of the kinematic connection propulsion (main) engine with a carrier (or curtain) of screws and other consumers of power, including the aggregates and systems necessary for the maintenance of the transmission and drives other power consumers.

The composition of the transmission:

  • - main and intermediate gearboxes;
  • - RV reducer;
  • - connecting and synchronizing shafts with couplings (elastic, cardan, splined, etc.) and their supports;
  • - fans of the oil cooling system;
  • - freewheel clutches (MSH);
  • - HB brake.


General requirements

Transmission together with its systems and established IA units it must be designed and constructed so that the expected operating conditions for life, the life of its critical failures (resulting in a catastrophic situation) per flight hour were estimated in accordance with the requirements.

If one or more engines fail (for a helicopter with more than one engine), the power from the running engines must be transmitted to the screws and other devices that ensure continuation of the flight and control of the helicopter. If all engines fail, the normal functioning of the screws in the autorotation mode and the operation of other devices necessary to control when the helicopter is lowered and planted should be maintained. The transmission is equipped with devices to automatically disconnect any engine from it if it is turned off or fails (for example, using the MAX).

The layout of the transmission must be capable of servicing and replacement of parts in accordance with the guidelines for the technical operation and maintenance.

To eliminate the difference in electrical potentials between the main elements of the transmission and the associated elements of the helicopter, it is necessary to provide, where possible, the connection of these elements to the total mass by direct contact or bridges of metallization. Auxiliary units should, as a rule, have a "weak link" to protect the transmission units from excessive torque. "Weak link" is designed so that in case of destruction of its fragments do not cause damage to other transmission units or other drives of helicopter systems. It is allowed to place a "weak link" in the drive from the transmission to the unit. The static and dynamic (fatigue) stresses and deformations of the entire nomenclature of the main parts and transmission units, as well as the vibration of the units and the attachment points of the transmission units, should not exceed certain values ​​(given the design features, materials used and the technology adopted). These values ​​are set taking into account operational experience and the results of bench tests and tests of serial and repair transmission units in order to confirm the adequacy of the static and fatigue strength of transmission assemblies (units), as well as the wear resistance of their parts.

The construction of the transmission must be within a certain time of operation (assigned resource) withstand repeated loads in operation without critical failure of the transmission.

Resources components (eg roller bearings) established on the basis of tests on the system of units (units) transmission.

Structural and kinematic scheme TRANSMISSION HELICOPTER

Transmission of single-rotor helicopter Mi-8 with PB (4.2.1) includes: a main gearbox (GR) 2; brake HB 3; tail shaft 4; an intermediate gear (PR) 5; intermediate shaft 6; reducer RV 7; Fan drive shaft oil-air radiator 1. Power to the drive NV and PB units, catering to the helicopter systems (pumps, hydraulic and lubrication systems, electrical generator, compressor and tachometer sensor), coming from the right and left engines through GR.

GR installed by helicopter to the struts podreduktornoy frame at the top of the helicopter. PR is designed to change the direction of power transfer. RV reducer changes the direction of power transmission from PR and lowers the frequency of rotation of the steering shaft.

helicopter Transmission

helicopter Transmission

The Hughes OH-6A light helicopter used the KKS transmission. A characteristic feature of this helicopter is the placement of the engine and air oil of the radiator 2, the use of a supercritical shaft 5 with a damper 4 and the absence of PR. The output of the gas jet into the rear part of the fuselage 7 reduces its aerodynamic resistance, and the drive of the oil cooler fan directly from the main shaft and the elimination of PR significantly reduce the total mass of the transmission.

The transmission peculiarity of the CH-47 Chinook helicopter is determined by its longitudinal scheme. It consists of gearboxes of the front and rear screws 1 and 7, a joint gearbox 3, two angle gearboxes 5 of motors 6, synchronizing shafts 4 connecting the motors with a joint gearbox.

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