Welded Body Hydraulic Cylinders
Welded body hydraulic cylinders have no tie rods. The barrel is welded directly to the end caps; the ports are welded to the barrel; the front rod gland is then usually threaded into or bolted to the cylinder barrel. This allows the piston rod assembly and the rod seals to be removed for service.
Welded body hydraulic cylinders have a number of advantages over tie rod style hydraulic cylinders: Welded cylinders have a narrower body and often a shorter overall length enabling them to fit better into the tight confines of machinery. Welded cylinders do not suffer from failure due to tie rod stretch at high pressures and long strokes. The welded design also lends itself to customization. Special features are easily added to the cylinder body. These may include special ports, custom mounts, valve manifolds, and so on.
The smooth outer body of welded cylinders also enables the design of multi-stage telescopic cylinders.
Welded body hydraulic cylinders dominate the mobile hydraulic equipment market such as construction equipment (including excavators, bulldozers) and material handling equipment (fork lift trucks, telehandlers, and tail lift gates). They are also used in heavy industry such as cranes, oil rigs, and large off road vehicles in above ground mining.
Piston Rod Construction: The piston rod of a hydraulic cylinder operates both inside and outside the barrel, and consequently both in and out of the hydraulic fluid and surrounding atmosphere.
Metallic Coatings: Smooth and hard surfaces are desirable on the outer diameter of the piston rod and slide rings for proper sealing. Corrosion resistance is also advantageous. A chromium layer may often be applied on the outer surfaces of these parts. However, chromium layers may be porous, thereby attracting moisture and eventually causing oxidation. In harsh marine environments, the steel is often treated with both a nickel layer and a chromium layer. Often 40 to 150 micrometer thick layers are applied. Sometimes solid stainless steel rods are used. High quality stainless steel such as AISI 316 may be used for low stress applications. Other stainless steels such as AISI 431 may also be used where there are higher stresses, but lower corrosion concerns.
Ceramic Coatings: Due to shortcomings of metallic materials, ceramic coatings were developed. Initially ceramic protection schemes seemed ideal, but porosity was higher than projected. Recently the corrosion resistant semi ceramic Lunac 2+ coatings were introduced. These hard coatings are non porous and do not suffer from high brittleness.
Lengths: Piston rods are generally available in lengths which are cut to suit the application. As the common rods have a soft or mild steel core, their ends can be welded or machined for a screw thread.
Our catalogue also shows a selection of the standard hydraulic cylinders / hydraulic rams that we regularly supply, including welded hydraulic cylinders – but if you are looking for a bespoke design then we can take care of that too! Just complete our Bespoke Cylinder Design Form and one of our hydraulic engineers will get back to you, or simply call them to discuss you requirements in detail.
And finally… as an ISO 9001 accredited company, we firmly believe that there are no better advocates than our customers. So if you need a little more convincing before you decide to give us a try, then here are a few case studies and testimonials for you to browse:
The Customer: Management, Engineering and Procurement Services Company to Offshore, Sub-sea and Oil and Gas Industries The Task: Hydraulics Online were contacted to provide pricing and a detailed... Find out more...
The Customer: Leading Manufacturer of Concrete Products The Task: Hydraulics Online were asked to design a complete... Find out more...