Conjunto de marcha à ré FAW: Um foco crítico em 5 Peças que podem ser reparadas

Bem-vindo a este guia técnico crítico sobre o Conjunto de marcha à ré FAW, o completo “idler” gearset for the manual transmission in the FAW Jiefang CA4251P66K24T1A3E5 6×4 trator semirreboque diesel. This assembly is solely responsible for enabling the vehicle to move backward.

O Conjunto de marcha à ré FAW is a high-strength gear system with a simple but critical logic. It is not in constant mesh with the main gearset. Em vez de, it is a separate “idler” gear that is physically moved into place by the driver’s shift linkage, intentionally reversing the flow of power to the main shaft.

Este guia detalhado é um recurso essencial para técnicos profissionais de transmissão e especialistas em peças.. Vamos desconstruir todo Conjunto de marcha à ré FAW em seu 5 componentes reparáveis, including the ‘Reverse idler gear’ (1701481-A7G), the ‘Idler shaft’ (1701482-A0L), its ‘Needle roller bearing’, and all critical locating hardware.

Componente principal: The ‘Reverse Idler Gear’ (1701481-A7G)

O coração do Conjunto de marcha à ré FAW is the ‘Reverse idler gear’ (1701481-A7G). Este é um serviço pesado, forged steel gear that is precisely engineered to handle the high-torque, low-speed demands of moving a fully-loaded tractor in reverse.

Unlike the helical-cut (angled) gears used for forward motion (which are quiet and smooth), this gear is typically a “spur” engrenagem, with straight-cut teeth. This straight-cut design is mechanically simpler and incredibly strong, able to withstand the high shock-load of being “slid” into mesh. This is what produces the characteristic “lamentar” sound when driving in reverse.

When the driver selects reverse, a shift fork slides this ‘Reverse idler gear’ into a very specific position: *between* the counter-shaft’s reverse drive gear and the main shaft’s reverse synchronizer sleeve. Este é o “lógica” do Conjunto de marcha à ré FAW. By introducing a third gear into the power path (Counter-shaft -> Idler Gear -> Main Shaft), it reverses the direction of the main shaft, causing the truck to move backward.

The teeth on this gear must be perfectly formed and hardened. A chipped or broken tooth on this single gear will make reverse inoperable and will send hardened steel fragments throughout the entire transmission, destroying other gears and bearings. This makes the quality of the Conjunto de marcha à ré FAW‘s main gear critical.

A Fundação: The ‘Idler shaft’ (1701482-A0L)

The ‘Reverse idler gear’ does not float; it spins on the ‘Idler shaft’ (1701482-A0L). This is the stationary “eixo” for the entire Conjunto de marcha à ré FAW. This shaft is a large-diameter, precision-ground, and case-hardened steel rod.

This shaft is mounted securely (often press-fit or bolted) into the transmission housing. It must be perfectly parallel to the main shaft and counter-shaft to ensure that when the idler gear slides into mesh, the gear teeth are perfectly aligned.

Any wear, scoring, or bending on this shaft is a critical failure. If the shaft is worn, the idler gear will be able to “oscilar” on its axis. This wobble will cause a loud, growling noise in reverse and, more dangerously, will prevent the gear teeth from meshing correctly. This can cause the gear to “pop out” under load or, no pior cenário, shatter the gear teeth. The ‘Idler shaft’ is the rigid foundation of the Conjunto de marcha à ré FAW.

Low-Friction Support: The Bearing (1701485-A7G)

The ‘Reverse idler gear’ (1701481-A7G) must be able to spin freely on the ‘Idler shaft’ with minimal friction. This is the job of the ‘Needle roller bearing’ (1701485-A7G). This is the key “anti-friction” componente do Conjunto de marcha à ré FAW.

This bearing is a “caged” set of small-diameter steel rollers (needles). It is pressed into the bore of the idler gear. This design is chosen for its extremely high **radial load capacity** in a very compact space. It allows the gear to support the immense separating forces created when the gear teeth are under torque.

This bearing is lubricated by the transmission’s “respingo” oiling system. A failure of this bearing is a common fault in a high-mileage Conjunto de marcha à ré FAW. It is typically diagnosed as a loud, agudo “lamentar” ou “rumble” that only occurs when the truck is in reverse (either moving or stationary with the clutch out). If this bearing collapses, the gear will seize to the shaft or be destroyed, resulting in a total loss of reverse.

Alignment & Segurança: Arruelas (1701487-A7G) e clipe circular (1701488-A7G)

The final two components of the Conjunto de marcha à ré FAW are responsible for “jogo final” control and security.

**’Gasket/Washer – reverse idler gear’ (1701487-A7G):** A lista de peças pede dois destes. These are not “Juntas”; they are **thrust washers**. These are hardened, precision-ground, and polished steel washers that are placed on either side of the idler gear (between the gear and the transmission case/circlip). Their job is to absorb the **axial load** (the fore-and-aft force) that is generated as the gear is slid into mesh. They provide a low-friction, replaceable wear surface. Worn-out thrust washers are a primary cause of a “sloppy” shifter feel or a transmission that “jumps” out of reverse.

**’Circlip – eixo de marcha lenta reversa’ (1701488-A7G):** This is the final retaining component. Este grande “snap ring” (circlip) is fitted into a groove cut into the ‘Idler shaft’. It acts as the final “hard stop,” preventing the entire assembly (the gear, consequência, and thrust washers) from sliding off the end of the shaft. It is a single-use part; a fatigued circlip that is re-used can fail, permitindo que toda Conjunto de marcha à ré FAW to fall apart inside the transmission.

FAW Reverse Gear Assembly Parts List

A tabela a seguir fornece o completo, detalhamento de todos 5 components identified in the ‘Reverse Gear Assembly’ diagrama para o trator FAW CA4251P66K24T1A3E5. Uma reconstrução do Conjunto de marcha à ré FAW requires replacing all bearings, arruelas, and circlips.

Especificações Técnicas e Contexto de Montagem

As especificações para o Conjunto de marcha à ré FAW são definidos por sua função como um motor de alto torque, sliding-mesh idler gear system. O inteiro Conjunto de marcha à ré FAW is a matched set of components.