Linde

In the field of hydraulics, Linde is one of the world’s leading manufacturers of high-pressure hydraulic components and modular drive systems. The company, now operating under the name LHY Powertrain and historically originating from Linde AG, develops and manufactures axial piston pumps, hydraulic motors, directional control valves, and electronic control systems for mobile machinery and stationary industrial equipment.

Company History and Development of Linde Hydraulics

The roots of Linde Hydraulik date back to 1904, when Hugo Güldner, Carl von Linde, and Georg von Krauss founded the Güldner-Motoren-Gesellschaft in Aschaffenburg. The company initially manufactured small diesel engines and expanded its product portfolio over the decades to include tractors and commercial vehicles. The true era of hydraulics began in 1956 with the so-called “Hydrocar, ” the first hydrostatically driven vehicle from Aschaffenburg. Two years later, in 1958, the first forklift with a hydrostatic drive system went into series production. This development marked the beginning of a long tradition in hydrostatic drive technology, which remains the technological foundation of Linde Hydraulik to this day.

In the 1960s, the company began supplying hydraulic components to external customers for the first time, thereby transforming itself from an internal drive division into an independent hydraulic supplier. In 1984, Linde introduced load-sensing valve technology, a milestone for efficiency and controllability in mobile hydraulics. This was followed in 1994 by the introduction of the 02 series, whose axial piston pumps and motors feature a characteristic swivel angle of 21 degrees. This design approach enables a larger displacement volume with a compact rotary unit and continues to define the product family to this day.

Shareholder Structure and Independence

In 2006, the hydraulics division became part of the KION Group. In December 2012, the hydraulics business was spun off as the independent company Linde Hydraulics GmbH & Co. KG, with the Chinese company Weichai Power acquiring a majority stake. Today, Weichai Power holds 90 percent of the shares, while the KION Group remains a minority shareholder with 10 percent. The company operates under the LHY Powertrain brand, though the name Linde Hydraulik remains firmly established among industry professionals. The headquarters remain in Aschaffenburg, with global manufacturing and sales locations.

Linde’s Product Portfolio and Core Components

Linde’s product portfolio covers the entire spectrum of high-pressure hydraulics: from axial piston pumps to hydraulic motors and directional control valves, as well as electronic control units and software solutions. These components are increasingly supplied as integrated drive systems from a single source, which distinguishes the company from pure component manufacturers.

02 Series Axial Piston Pumps

The 02 series forms the core of Linde’s pump portfolio. It is divided into two main lines: the HPR-02 for open circuits and the HPV-02 for closed circuits. Both lines are based on a swivel-plate design with a 21-degree swivel angle, which enables a high displacement volume in a compact design.

The HPR-02 is a self-regulating, variable-displacement axial piston pump for open circuits. It automatically adjusts its flow rate to match load requirements, which is why Linde refers to it as self-regulating. The pump features several control concepts that can be combined:

• Load-sensing controller: Adjusts the flow rate so that the pump pressure is only slightly above the highest load pressure. This minimizes throttling losses and reduces energy consumption.
• Pressure cut-off: Reduces the displacement volume when the system pressure reaches a preset limit to prevent overload.
• Power controller: Keeps power consumption within the motor’s limits by reducing the displacement volume accordingly as pressure rises.

The HPV-02 is used in closed hydrostatic circuits, typically in travel drives and swing mechanisms of excavators, wheel loaders, and telescopic cranes. It offers nominal pressures up to 450 bar and peak pressures up to 500 bar. Adjustment is performed either mechanically-hydraulically via a control rail or electrohydraulically via proportional solenoids controlled by a vehicle control unit.

Hydraulic Motors and Drive Concepts

Linde supplies compatible hydraulic motors for the 02 series, which are divided into variable-displacement motors and fixed-displacement motors. The variable-displacement motors adjust their displacement to changing load and speed conditions. This is particularly important in hydrostatic travel drives, where high starting torque is required in the low-speed range and a smaller displacement ensures higher final speeds in the higher-speed range.

Constant-displacement motors with a fixed displacement are used where robust, consistent torque delivery is required, such as in swivel mechanisms. The motors in the 02 series are available as swivel-plate and inclined-axis motors, depending on the requirements for power density and installation conditions.

Directional Valves and Valve Systems

Linde’s valve portfolio includes individually deployable directional control valves, valve blocks, and valve modules for multi-function machines, as well as control plates for integrated manifold solutions. The valves utilize load-sensing technology, which the company introduced as early as 1984. This technology ensures that the pump delivers only as much flow as the consumers actually require, based on the highest load pressure at any given time.

LSC Synchron Control System from Linde

The Linde Synchron Control System, or LSC for short, represents a key technology driver for the company. It coordinates HPR pumps, valve blocks, and actuators so that multiple hydraulic functions of a machine can be operated simultaneously and smoothly, even when the pump has reached its maximum flow capacity.

The LSC system is based on the load-sensing principle: Each consumer valve sends a load pressure signal to the pump, which adjusts its flow rate accordingly. If the sum of all requested flow rates exceeds the pump’s capacity, the Synchron-Control function kicks in. It reduces the individual flow rates proportionally to one another, ensuring that the relative speeds of the movements are maintained. An excavator that simultaneously raises the boom and closes the bucket thus maintains its motion pattern, even when the engine is operating at its power limit.

This is achieved through dedicated LSC control blocks, integrated sensors, and electronic control logic. The system can be combined with open hydraulic circuits and closed travel drives. The benefits include reduced throttling losses, lower fuel consumption, and more responsive machine control.

Electrohydraulic Integration and System Approach

Linde positions itself not merely as a component supplier, but as a system provider. The electronic level of the products includes control units, joysticks, sensors, actuators, and application-specific software. The control units coordinate hydrostatic travel drives and work functions, record sensor values, and perform diagnostics. Proportional pilot valves and electrohydraulic pump adjustments enable closed-loop control, which allows for precise regulation of speed, torque, and direction of travel.

Integrated Drive Systems

In addition to individual components, Linde supplies complete drive systems. These include hydrostatic CVT solutions, hydrostatic variators for internal and external transmission integration, as well as combinations of pumps, motors, and transmissions for travel, swing, and track drives. These systems are designed for mobile machinery, where OEMs value a modular, configurable drive solution from a single source.

Industries and Applications

Linde Hydraulik’s products are found in a wide range of industries:

• Construction machinery: Excavators, wheel loaders, telescopic loaders, and cranes use hydrostatic travel drives, swing mechanisms, and working circuits.
• Agricultural machinery: Tractors and harvesters benefit from CVT drives and load-sensing systems.
• Material handling: Forklifts and industrial trucks with hydrostatic power transmission.
• Special-purpose machinery and industrial equipment: Presses, mixing plants, and port equipment with hydraulic drives.

Maintenance and Service of Linde Hydraulic Components

The service life of Linde components depends largely on the cleanliness of the hydraulic fluid and adherence to maintenance intervals. The 02 series is designed for high continuous loads; however, seals, bearings, and sliding surfaces are subject to hydraulic wear. Regular oil sampling, filter changes, and seal inspections are standard maintenance tasks. During commissioning and when replacing components, the housing pressure limits must be observed; for the 02 series, these are 2.5 bar absolute. Strict adherence to the permissible nominal pressures and the use of approved hydraulic oils prevent premature damage to the rotary units.