Classification of hydraulic cylinder applications
Cylinder manufacturers offer a wide range of cylinder options, helping to achieve the application and performance requirements. Many of the design options are according to international and national industrial standards, but several industries have their own design guidelines as well.
In case of specification of a hydraulic cylinder several factors must be taken into consideration:
- Capacity (load capability) of the cylinder
- Stroke distance requirement
- Linear moving speed
- Operating temperature range (minimum and maximum values)
- Mounting style
- Piston rod size
- Cylinder configuration
- Rod ends, rod threading
- Seal system
As it is illustrated by above list, seal components – among the other factors – must be considered even during the cylinder specification. Why it is so important? Because seal performance and reliability are essential to the overall performance of the cylinders. That is why appropriate seal and seal system selection is required. Selection will be influenced by the cylinder type, design and by the operating and environmental conditions.
There is no industrial standard established or available for classification of cylinder application and/or operating conditions. However, it is still important to set certain criteria and parameter limits that help to describe and classify the hydraulic cylinder applications. The suggested criteria, parameter limits and classification are according to the chart below
| Application parameters | HYDRAULIC CYLINDER APPLICATION CLASSES | ||
| Light-duty | Medium-duty | Heavy-duty | |
| System pressure MPa (psi) | 14 (2000) | 25 (3625) | 40+ (5800+) |
| Pressure peaks | None or rare and low | Moderated, what does not exceed the system pressure significantly in combination with short duration | High pressure peaks, what can exceed the system pressure several times. Can occur often in combination with longer duration. |
| Temperature range °C (°F) | Up to 60 (140) | Up to 80 (176) | Exceeding 80 (176) with peaks in excess of 120 (248) |
| Surface speed m/s (ft/min) | 0.1 (20) | 0.5 (100) | 1.0 (200) |
| Side loading | None to minimal side load on guide components (short stroke cylinders and cylinders are in vertical position) | Moderate side load on guide components (medium stroke cylinders and cylinders close to vertical position) | Heavy side load on guide components (large cylinders, heavy components). Long stroke cylinders and cylinders are in horizontal position |
| Environment | Low temperature fluctuation | Moderate temperature fluctuation | High temperature fluctuation |
| Contamination | Free or low | Moderate (or cylinder in horizontal, down-stroke position) | Harsh environment with high contamination (cylinder is in vertical, up-stroke position) |
