The need to replace hoses is quite common on hydraulic presses. Hydraulic hose manufacturing is a big industry, the competition is fierce, and there are a lot of cowboys running around. Therefore, if you own or are responsible for hydraulic equipment, where you buy replacement hoses, how they are made, cleaned and stored, should be considered before installing them on your machine.
In the process of manufacturing a hose, or rather, in the process of cutting a hose, contamination appears in the form of metal particles from the reinforcement of the hose and the cutting blades themselves, as well as polymer dust from the outer layer of the hose and the inner pipe.
The amount of contaminants entering the hose during cutting can be reduced by using methods such as using a wet cutting blade instead of a dry cutting blade, blowing clean air into the hose while cutting it, and/or using a vacuum extraction device. The last two are not very practical when cutting long hoses from a reel or with a moving hose cart.
Rice. 1. Dennis Kemper, Gates Product Applications Engineer, flushes hoses with cleaning fluid in the Gates Customer Solution Center.
Therefore, the focus must be on the effective removal of these cutting residues, as well as any other contaminants that may be present in the hose, prior to installation. The most effective, and therefore the most popular, method is to blow cleaning foam shells through a hose using a special nozzle connected to compressed air. If you’re unfamiliar with this device, search Google for “hydraulic hose rig”.
The manufacturers of these cleaning systems claim to achieve hose cleanliness levels in accordance with ISO 4406 13/10. But like most things, the results achieved depend on a number of variables, including using the correct diameter projectile to clear the hose, whether the projectile is used with dry or wet solvent, and the number of shots fired. Generally, the more shots, the cleaner the hose assembly. Also, if the hose to be cleaned is new, it should be shot-blasted before crimping the ends.
Horror Hose Stories Almost every hydraulic hose manufacturer owns and uses hoses to clean projectiles these days, but how thoroughly they do it is another matter entirely. This means that if you want a hose assembly to meet a certain cleanliness standard, you must specify and adhere to it, as evidenced by the following instructions from Heavy Equipment Mechanics:
“I was replacing some hoses on a Komatsu 300 HD for a customer and he noticed that I was washing the hoses before I put them on. So he asked, ‘They wash them when they are made, don’t they?’ I said, ‘Of course, but I love checking. “I removed the cap from the new hose, rinsed it with solvent, and poured the contents onto a paper towel while he watched. His answer was “holy (expletive).”
It’s not just cleanliness standards that need to be observed. A few years ago, I was at a customer’s site when a hose supplier came to the customer with a large quantity of hose assemblies. As the pallets come off the truck, anyone with eyes can clearly see that none of the hoses are capped to prevent contaminants from entering. And clients accept them. nut. Once I saw what was going on, I advised my customer to require that all hoses come with plugs installed, or not accept it.
Scuffs and Bends No hose manufacturer will tolerate this kind of fuss. Moreover, it is definitely not something that can be left alone!
When it’s time to install a replacement hose, in addition to keeping it clean, pay close attention to the gasket, make sure all clamps are tight and tight, and if necessary, use a cheap PE spiral wrap to protect the hose from abrasion.
Hydraulic hose manufacturers estimate that 80% of hose failures can be attributed to external physical damage resulting from hose being pulled, kinked, pinched, or chafed. Abrasion from hoses rubbing against each other or against surrounding surfaces is the most common type of damage.
Another cause of premature hose failure is multi-plane bending. Bending a hydraulic hose in several planes can lead to twisting of its wire reinforcement. A 5 degree twist can shorten the life of a high pressure hydraulic hose by 70%, and a 7 degree twist can reduce the life of a high pressure hydraulic hose by 90%.
Multi-planar bends are usually the result of improper selection and/or routing of hose components, but can also be the result of inadequate or insecure hose clamping when the machine or drive is in motion.
Attention to these often overlooked details not only ensures that changing hoses will not cause contamination and possible collateral damage to the hydraulic system they belong to, but that they will last as they should!
Brendan Casey has over 20 years of experience servicing, repairing and overhauling mobile and industrial equipment. For more information on lowering operating costs and increasing…
Post time: Jan-20-2023