Case CX37C Mini Excavator Service Manual

Description

Table of Contents

1. Content
2. Introduction
3. Engine
4. Hydraulics System
5. Frames and Ballasting
6. Tracks and Track Suspension
7. Electrical System
8. Booms, dippers and buckets
9. Platform, cab, bodywork and decals
10. Electrical Schematic
11. Hydraulic Schematic

Manual Extract: Hydraulic systems Boom up circuit

When the right-hand control lever is pulled back, the boom spools in the main control valve are moved to the up position by the pilot oil pressure from the remote control valve.
The oil from the P1 and P3 pump flows into the main control valve and then goes to the large chamber of boom cylinders.
At the same time, the oil from the small chamber of boom cylinders returns to the hydraulic oil tank through the boom spool in the main control valve.

When this happens, the boom goes up.
The excessive pressure in the boom cylinder bottom end circuit is prevented by relief valve (Rv).
When the boom is up and the control lever is returned to neutral position, the circuit for the holding pressure at the bottom end of the boom cylinder is closed by the boom holding valve (2).
This prevents the hydraulic drift of boom cylinder.