In industrial manufacturing, agricultural machinery, engineering machinery and other scenarios, tie rod hydraulic cylinders are indispensable hydraulic actuators.
This article will provide you with a systematic analysis of the tie rod hydraulic cylinder. We hope this will help you fully understand the practical characteristics and application value of this key hydraulic component.
What is the Tie Rod Hydraulic Cylinder？
The tie rod hydraulic cylinder is a commonly used hydraulic actuator. It uses a set of high-strength threaded steel rods to fasten the end caps at both ends of the cylinder together. It can convert hydraulic energy into linear mechanical motion, which is used to drive or pull mechanical components.
Tie Rod Hydraulic Cylinder Parts
Cylinder Barrel
The cylinder barrel is the structure that bears internal hydraulic pressure. And it is usually made of high-strength seamless steel tubes. Its internal space is used to accommodate hydraulic oil, pistons, and piston rods.
The inner wall of the cylinder barrel has been machined precisely, which can reduce the friction during the movement of the piston. And the wall thickness of the cylinder barrel will be designed according to the working pressure.
Piston
The piston is the core component that converts hydraulic energy into mechanical energy. It is installed inside the cylinder barrel, and its material is mostly wear-resistant metal or ductile iron.
Piston Rod
One end of the piston rod is fixedly connected to the piston. The other end extends to the outside of the cylinder body for connecting the load. The piston rod is usually made of materials that are wear-resistant and corrosion-resistant.
The piston rod can transmit thrust or tension to external devices. It is a key conductive component that connects internal power and external operations.
End Caps
The end caps are installed at both ends of the cylinder barrel. They serve to seal the cylinder body and support the internal components. The structure of the end cap is adapted to the through fixing requirements of the pull rod. At the same time, it will reserve appropriate channels for the extension of the piston rod and the inflow and outflow of hydraulic oil.
Tie Rods
The tie rods are evenly distributed and extend through the front and rear end caps as well as the cylinder barrel. It fixes the entire cylinder structure through the tightening action of the locking nut.
The tie rod can disperse the tension generated by the internal pressure of the cylinder. This ensures the structural stability of the cylinder body under high-pressure conditions.
The tie rod hydraulic cylinder with a small bore diameter usually employs 4 high-strength threaded tie rods, while hydraulic cylinders with a larger bore diameter may require 16 or 20 tie rods.
Seals
The seals are distributed around the piston and the piston rod. It can prevent the leakage of hydraulic oil and also prevent external dust and impurities from entering the cylinder body. Different working conditions require the use of appropriate sealing materials to ensure the sealing effect.
How does the Tie Rod Hydraulic Cylinder Work?
The working principle of the tie rod hydraulic cylinder is based on Pascal’s law. It drives the load through the hydraulic pressure within a closed hydraulic system.
The hydraulic pump pressurises the hydraulic oil and injects the pressurised oil into the closed chamber at one end of the hydraulic cylinder through the oil port. The oil pressure acts on the surface of the piston and generates a thrust. This thrust pushes the piston and the connected piston rod outward, thereby driving the load to perform work.
The Type of Tie Rod Hydraulic Cylinder
Single Acting Tie Rod Hydraulic Cylinder
A single acting pull rod hydraulic cylinder refers to a type that relies solely on hydraulic oil to provide power in one direction. It injects high-pressure oil into the chamber on one side of the piston through a single oil port, pushing the piston rod to extend and work.
The return stroke of a single acting tie rod hydraulic cylinder relies on external forces such as spring elasticity and load gravity to achieve reset. Its structure is simple and the cost is low. The single acting tie rod hydraulic cylinder is suitable for simple working conditions such as clamping devices, jacks, and lifting platforms that only require one-way thrust.
Double Acting Tie Rod Hydraulic Cylinder
The double acting tie rod hydraulic cylinder is the most common type. The extension and retraction movements of its piston rod are both controlled by hydraulic oil.
The double acting tie rod hydraulic cylinder has two separate oil chambers. It controls high-pressure oil to alternately enter both sides of the piston through a directional valve, driving the piston rod to extend and retract respectively.
It has better control and higher efficiency. It is widely used in industrial automation, construction machinery and other scenarios that require reciprocating linear motion.
NFPA Tie Rod Hydraulic Cylinders
The NFPA standard tie rod hydraulic cylinder follows the unified standard established by the National Fluid Power Association (NFPA) in the United States. The NFPA standards provide detailed specifications for key parameters of hydraulic cylinders, including cylinder diameter, piston rod diameter, installation dimensions, and pull rod specifications.
So NFPA tie rod hydraulic cylinders of the same specification have a high degree of interchangeability. It is a widely used tie rod hydraulic cylinder in the North American market and many international markets.
Metric Tie Rod Hydraulic Cylinder
The metric tie rod hydraulic cylinder is a type that is designed and manufactured strictly in accordance with the international metric unit system. All key dimensions, such as cylinder bore diameter, piston rod diameter, stroke, installation threads, and hole spacing, are measured in millimetres.
The metric tie rod hydraulic cylinder usually complies with the ISO standard and is compatible with most hydraulic systems in the world.
The Advantages of the Tie Rod Hydraulic Cylinder
Sturdy and Durable
The external tie rod of the hydraulic cylinder serves as a connection point and also forms a protective and sturdy framework. This framework can effectively resist physical damage caused by external impacts and misoperation, providing protection for the internal cylinder and sealing system.
High Carrying Capacity
Multiple high-strength tie rods are evenly distributed and pre-tightened, which creates a highly tensile structure for the tie rod hydraulic cylinder. When the cylinder is subjected to high pressure, the tie rod can evenly distribute the huge thrust received by the end cap. This ensures that there is no leakage or deformation at the connection of the cylinder block.
This design makes the tie rod hydraulic cylinder have stable and reliable load-bearing performance. It ensures the structural integrity and safety of the tie rod hydraulic cylinder working for a long time under high pressure.
Most tie rod hydraulic cylinders can withstand a pressure of 2500 psi, while some heavy-duty tie rod hydraulic cylinders can even withstand a pressure of 3000 psi.
Easy Maintenance
The tie rod hydraulic cylinder adopts a modular tie rod connection structure, and you only need to loosen the tie rod nut to complete the overall disassembly. Sealing components, piston rods and other easily damaged parts can be replaced quickly on-site.
This can shorten the equipment downtime for maintenance and reduce the manpower and time costs for maintenance.
High Degree of Standardisation
Most tie rod hydraulic cylinders comply with international standards such as ISO and NFPA. Their dimensions, cylinder diameters, stroke lengths, and other parameters all follow a unified standard. This provides convenience for your purchase, use and maintenance.
Flexible Installation
There are various installation methods for tie rod hydraulic cylinders. It can flexibly adjust the installation angle according to the layout of the equipment space.
For some models, the tie rod hydraulic cylinders adopt a compact design, which optimises the volume and weight while maintaining the load-bearing capacity. Even in a space-constrained environment, you can still install it smoothly. It is suitable for various scenarios such as industrial machinery and agricultural equipment.
What Factors need to be Considered when Choosing a Tie Rod Hydraulic Cylinder？
Working Pressure
The pressure requirements for tie rod hydraulic cylinders vary depending on the different application scenarios. When making the selection, you need to confirm that the rated pressure of the tie rod hydraulic cylinder can match the maximum working pressure of your system.
The appropriate pressure level is necessary to ensure that the tie rod hydraulic cylinder can output force stably during operation and will not be damaged prematurely due to overload.
Load Demand
When choosing a tie rod hydraulic cylinder, you need to clearly determine the weight and force that your system needs to push or pull. The inner diameter of the cylinder and the oil pressure of the system jointly determine the force that the tie rod hydraulic cylinder can generate.
It is important to know that the equipment you choose can meet the actual load requirements. This can avoid performance degradation or premature damage due to insufficient power or overloading.
If your working conditions involve lateral forces or impact loads, you need to increase the cylinder diameter appropriately or choose a thicker piston rod to enhance the structural load-bearing capacity.
Stroke Length and Movement Range
The stroke length of the tie rod hydraulic cylinder is the distance that the piston moves back and forth within the cylinder. This parameter will affect the actual movable range of the equipment.
If the stroke length is too short, it will limit the operational capability of the equipment. If it is too long, it may lead to space waste or installation difficulties. So you need to precisely measure the maximum moving distance required for the piston rod based on the actual motion requirements of the equipment.
Material
The durability of the tie rod hydraulic cylinder is related to the construction materials and processing quality. In harsh environments or high-intensity load conditions, high-strength steel, corrosion-resistant materials, and cylinder bodies with protective treatment can extend their service life.
You need to select the appropriate materials and manufacturing processes based on the working conditions. This will help enhance the overall reliability of the equipment.
Installation Method
The installation method of the tie rod hydraulic cylinder will affect its stability. You need to choose a suitable installation method based on the spatial layout, movement direction, and installation support requirements of the device.
The common installation methods of tie rod hydraulic cylinders include flange mount, clevis mount, trunnion mount, foot mount, and extended tie rod mount.
The Application of Tie Rod Hydraulic Cylinders
Industrial Manufacturing
The tie rod hydraulic cylinder is widely used in different mechanical equipment. For example, in stamping machines, assembly lines and forming equipment, the tie rod hydraulic cylinder is responsible for pushing, positioning or clamping workpieces.
The tie rod hydraulic cylinder can provide stable linear force output and is an indispensable component in many automation and production processes.
Engineering Machinery
The tie rod hydraulic cylinder can be used in equipment such as excavators and loaders. It can drive the bucket arm, the telescopic mechanical arm or adjust the mechanical posture to complete the tasks of lifting, moving and positioning heavy components.
Agricultural Machinery
The tie rod hydraulic cylinder is commonly used in agricultural equipment such as tractors, harvesters, and planters. It can perform actions such as lifting, tilting and controlling various farming tools.
For example, in the tractor suspension system, the operating angle between the agricultural machinery and the ground is adjusted through tie rod hydraulic cylinders. Then, the depth of ploughing and the precision of sowing are controlled.
Logistics and Warehousing
The tie rod hydraulic cylinder is commonly found in forklifts, scissor lifts, and conveying systems. It is used to achieve the lifting, tilting or movement of the load.
The pull rod hydraulic cylinder can complete loading, unloading, stacking and other operations while maintaining a stable load. It is an important component of modern warehousing and logistics systems.
Mining and Heavy Duty Applications
The tie rod hydraulic cylinder is also commonly used in mines and other heavy-duty machinery, such as loaders, rock drilling equipment, and transport vehicles. In these harsh scenarios, it can withstand high-intensity, long-term repetitive push-pull tasks and demonstrate good durability and reliability.
FAQs
Under what Circumstances will the Tie Rod Hydraulic Cylinder Experience Bending of the Piston Rod or Elongation of the Tie Rod?
The bending of the piston rod is usually caused by lateral loads or poor alignment during installation. The elongation deformation of the tie rod may be caused by long-term ultra-high pressure cyclic loads and continuous equipment vibration.
If you did not tighten the components to the standard torque value during the initial assembly, it could also cause the tie rod to deform.
Why is the Torque of the Tie Rod Important for the Lifespan of the Tie Rod Hydraulic Cylinder?
The tightening torque of the tie rod directly affects the sealing effect and overall rigidity of the tie rod hydraulic cylinder.
If the torque of the tie rod is too loose, the sealing element will not reach the required compression degree as designed, which may lead to oil leakage. If the torque of the tie rod is too tight, it will cause slight deformation of the cylinder barrel and accelerate the wear rate of the seals.
So you should tighten all the pull rods evenly according to the recommended torque value.
What should be Noted when the Tie Rod Hydraulic Cylinder is not Used or Stored for a Long Time?
When storing, you should keep the cylinder body and the piston rod clean, apply anti-rust oil, and place them in a dry environment. Do not keep the piston rod exposed at the maximum stroke position for a long time. This will cause surface corrosion.
In addition, you should regularly check the aging condition of the rubber seals during storage. If you find that the seals have failed before resuming operation, you need to replace them in time.
Why does the Pressure Drop or Insufficient Thrust Occur during the Operation of the Tie Rod Hydraulic Cylinder?
This phenomenon is usually caused by internal leakage or problems with the hydraulic oil. Internal leakage can cause the pressure chamber to be unable to maintain the required pressure and result in insufficient thrust.
Mixing air or pollutants into the oil can also affect the transmission of pressure . You can check the sealing condition and keep the oil clean.
What Causes Vibration or Abnormal Noise when Using the Tie Rod Hydraulic Cylinder?
Vibration and abnormal noise may be caused by air being mixed into the hydraulic system, wear of the seals, bending of the piston rod, or excessive clearance between the internal moving parts.
You can open the exhaust valve to exhaust the system air, check the condition of the seals and piston rods. Meanwhile, you should confirm whether the internal component clearances are within the standard range.
Final Thoughts
The tie rod hydraulic cylinder, with its significant advantages of easy maintenance, simple structure, and wide installation adaptability, can match the working conditions of multiple industries.
According to the individualized needs of different scenarios, we can offer you comprehensive customized services. Please feel free to contact us at any time for professional advice or customized solutions. We will help you choose a most suitable tie rod hydraulic cylinder product.
