一.Product Name

Flange for lower connecting plate of boom on Zoom lion truck-mounted cranes, suitable for 20-tonne, 25-tonne, 50-tonne, 70-tonne and 80-tonne models.

二.Adaptation model

suitable for 20-tonne, 25-tonne, 50-tonne, 70-tonne and 80-tonne models.

三.Product Role

Within a crane hydraulic system, the central swivel joint transfers oil from the stationary lower carriage to the continuously slewing upper structure. The “flange joint” at its very bottom end fulfils four main tasks:
1. Rigidly anchors the whole joint to the chassis
A ring of threaded holes in the flange lets it be bolted to the lower-carriage bracket, creating a rigid interface that resists both axial loads and slewing torque and ensures the housing (the fixed member) never rotates with the spindle.
2. Acts as a high-flow, low-pressure-loss transition manifold
The internal cavity of the flange opens directly into the housing’s annular oil chambers, working like an “integrated distributor”. Several large-bore pipes from the lower structure can be connected to mounting ports on the side or bottom face of the flange; from there the oil is fed evenly into the individual sealed channels, avoiding the pressure drop that would occur with sharp reductions in diameter.
3. Provides the first high-pressure seal and an easily separable sealing surface
The flange face can be machined in one pass with seal grooves that accept O-rings or bonded seals. When the flange is mated to the valve plate on the chassis it forms a static face seal. For maintenance, only the flange bolts have to be loosened; the entire swivel joint can then be lifted out without disconnecting multiple hard-lines.
4. Incorporates positioning and anti-loosening features
In newer designs the underside of the flange carries a slide-slot and locating-block mechanism that allows rapid angular alignment and prevents the bolts from backing off under working vibration.
In short, the crane’s central-swivel “flange joint” is simultaneously the “connection flange” that locks the joint to the chassis, the “distribution flange” that brings multiple high-pressure oil lines into the joint, and the “service flange” that lets the whole assembly be removed in one piece for future maintenance.

四.Product Details