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5 Hydraulic Hose, Fittings, and Cylinder FAQs with Step-by-Step Answers

5 Hydraulic Hose, Fittings, and Cylinder FAQs with Step-by-Step Answers

October 2, 2020

5 Hydraulic Hose, Fittings, and Cylinder FAQs with Step-by-Step Answers


What is a Hydraulic Hose?

This is a high-pressure thermoplastic or synthetic rubber used in a hydraulic system, usually in between two fluid ports. It is surrounded by windings mainly made out of metal or fiber that enhance its strength. The windings offer reinforcements in strength and flexibility and are either spiral wound or braided. Hydraulic hoses comprise three parts: an inner tube that carries fluid, a sheath of spiral wound wire or braided wire, and an outer protective wire designed to withstand harsh weather conditions, abrasions, or chemicals. A hydraulic hose is used in various industrial systems, with considerations being placed on critical parameters such as performance specifications, constructions options, and dimensions. Hydraulic hose sizes are based on the inside and the outside diameter of the hose. The functionality of a hydraulic hose is dependent on the mechanical bending limit of reinforcement and acceptable hose cross-section deformation. Hydraulic hoses serve two main functions: to reduce the impact of vibrations as well as to allow movement between 2 port locations. They can also be used to enhance ease of installation and dampen the noise between vibrating components. The flexibility of the pipe allows it to line up with ports that are not well aligned and require that the pipe or tube must be more accurate to fit the installation due to their rigidity. For a hydraulic hose to function in between two moving components, it must have an appropriate pressure rating, material construction, and diameter, which directly impacts its flexibility. They are also equipped with cable carriers, tractor implements, and hydraulic presses.


How Do I Replace a Hydraulic Hose?

Hydraulic hoses wear out over time, resulting in leakages or malfunction. Here is a step by step guide on how to replace a hydraulic hose How to have the damaged hose removed Step 1: Wear protective clothing Hydraulic fluid is toxic to the skin and could injure any part of the body it comes into contact with. Wear gloves to protect your hands and goggles to protect your eyes. Wear clothing that covers your other body parts, such as coats with long sleeves or pants. These should be worn throughout until the replacement process is complete. Where your work area is not ventilated, wear a respirator or mask. Step 2: Allow pressure out of the hydraulic system Working on the hydraulic system with its pressure could result in injuries from the hydraulic fluid spraying on you. The process of releasing tension from the hydraulic hose is available on the user manual and varies with each equipment. One of the most common ways of releasing pressure involves pulling a lever on the hydraulic system the releases pressure. You can push this lever back and forth several times to push excess pressure out. For equipment that raises like a backhoe, ensure you lower the mechanism on the ground before proceeding to work. Step 3: Place a bucket or a sheet beneath the component you are replacing A sheet or bucket prevents contamination of your work area from the hydraulic fluid that leaks out when replacing a hose. Step 4: Remove coverings on the hose attachment To be able to work on it, remove any coverings on it. You must keep track of what you remove and follow the user manual for the exact process to be followed. Step 5: Clean the connectors on both sides of the hose Dirt, grime, and dust often build up on both ends of the hose and should be cleaned up with a rag Step 6: Use a wrench to unscrew the fittings on the hose Installing a new hydraulic hose Step 1: Choose one that has accurate specifications of the old one. If you are not sure about the specifications, carry the old one with you when making a purchase. If your component is in a position where there is friction between it and other machines or pipes, consider placing an abrasive sleeve.  Step 2: Ensure all the connectors and fitting are clean before installing them. Once this is done, install one side of the hose into the fitting and rotate clockwise in order to tighten it. Installing the final side is trickier as the component cannot rotate freely and requires the use of two wrenches. Begin by installing the hose into the connector and holding it in place using a wrench. Rotate the connector until it cant spin further. Step 3: Replace all the coverings removed before installation and compare it with the user manual for accuracy.  Step 4: Once this is achieved, test the hydraulic systems under low pressure.


How Do I Make a Hydraulic Hose?

Step 1: Have the right tools and materials for the project  These are:
  • Hydraulic hose
  • Calipers
  • Hose lubricant 
  • Chalk
  • Safety gloves and googles
  • Crimping machine, die, and collar
  • Hydraulic fitting
Step 2: Take measurements and make cuttings Measure the desired length and cut to the required measurements. Use a file to make the ends smooth. Step 3: Choose a fitting series Before choosing a fitting series, put into consideration such factors as orientation, working pressure, style and type, and material that will ensure corrosion resistance. You mustn't make an interchange of the fittings and brands. Step 4: Note the insertion depth and push on the fittings Use an insertion depth block to determine the insertion depth. Mark a thick chalk line to note the depth and push the hose into the fitting until the mark is reached. Step 5: Check on crimper setting and adjust them accordingly Crimpers are designed to crimp certain diameters. Adjust the settings accordingly and ensure you choose the correct crimp diameter for each hose assembly. Step 6: Identify the appropriate crimper die set Using the crimper decal, identify the crimper dies designed for your hoses and fittings. The Crimpsource is a good source for technical specifications. Step 7: Insert the end of the hose into the crimping machine The hose should go through the die with the top concealed inside the fitting but not above the die. Step 8: Have the compression ring on the step of the adapter bowl Refer to the decal on the to identify appropriate tools. Step 9: Wear your protective clothing and crimp it With your protective gear on, turn on the machine. Verify the crimp diameter. Once done, ensure the assembly is clean. Step 10: Cap the assembly on both ends Insert a cap on the fitting end and use a heat shrink machine to ensure there is no contamination on the assembly. What is the Difference Between a Single-Acting and a Double-Acting Cylinder? The Double-Acting cylinder has a port on each end of the cylinder, to allow for the hydraulic fluid to be supplied to aid in the extension and retraction of the cylinder.  In comparison, a single acting cylinder the hydraulic fluid passes through the port at one end of the cylinder, which extends the rod by means of the area difference. In this type of cylinder, the piston rod is retracted by either an external force, or through the pull of gravity. 


How Do I Identify the Proper Hydraulic Fitting?

Step 1: Determine the type of fitting Is the fitting crimped (permanant) or reusable? More than likely, the fitting is crimped  since most newer equipment requires a crimping tool for installation. Step 2: Match the port connection with the hose connection It’s important to match the port connection with the corresponding hose connection. Use this table to help determine the proper connection.
Port Connection Hose Connection
BSPP (JIS-PF) 60 degree NPSM Swivel
BSPT (JIS-PT) 30 degree Flare (Metric)
DIN Metric O-Ring Face Seal (ORFS)
ISO 6149 24 degree Flareless (DIN)
JIS-B2351 30 degree Flare (BSPP)
Metric Taper 45 degree Flare
NPT/NPTF 37 degree Flare
SAE Straight Thread 24 degree Flareless (SAE)
Step 3: Determine the type of sealing Based on the technical characteristics and physical dimensions, is the sealing type a O-Ring, Mated Angle, or Tapered Thread. The O-Ring will include the seal, the Mated Angle is based on two thread types: straight and parallel and the male and female units will form the seal together, and the Tapared Thread with the inside thread being female and the outside thread male. Step 4: Determine the fitting design and size of the thread To determine the design fitting and thread size, click here