---
publication_id: "OT-2026-000003156"
title: "Control apparatus for hydraulic excavator"
published_at: "2026-09-15T19:40:24.239068Z"
canonical_url: "https://opentechnical.org/p/OT-2026-000003156"
categories:
  - "industrial-motion-power-transmission/fluid-power"
keywords:
  - "f15b11/17"
  - "f15b11/17"
  - "e02f9/2203"
  - "e02f9/2203"
  - "e02f9/2228"
  - "e02f9/2228"
---

# Control apparatus for hydraulic excavator

## Abstract

Pressure sensors sense a pilot pressure Pa corresponding to the amount of boom raising operation of a boom operation lever and a pilot pressure Pb corresponding to the amount of arm pulling operation of an arm operation lever. When the condition of Pa>Pb is met during the horizontal pulling operation, the rate of supply of the working fluid to an arm actuating cylinder is reduced to a rate corresponding to the amount of operation of the operation lever. Conversely, when the condition Pa<Pb is met, the rate of supply of the working fluid to the boom actuating cylinder 5 is reduced to a rate corresponding to the amount of operation of the operating lever. Horizontal pulling operation for levelling the ground can be conducted without requiring high level of skill. The horizontal pulling work can be done easily and smoothly, while preventing the bucket from cutting into the ground and from floating above the ground.

## 1. Drawings

[0001] Sheet 1.

[0002] Sheet 2.

[0003] Sheet 3.

[0004] Sheet 4.

[0005] Sheet 5.

[0006] Sheet 6.

[0007] Sheet 7.

[0008] Sheet 8.

[0009] Sheet 9.

[0010] Sheet 10.