1. Measure and mark exactly

  2. Always bend in the same direction

  3. Clamp tubing securely in bender

  4. Make certain the length mark is tangent to the desired angle on the radius block or in line with the desired degree on the link member

  5. Bend accurately to the desired angle plus spring-back allowance

  6. Remove tube and double-check bend angle

  7. Check measurement length with tape or a rule

Clamping —

With correct routing and bending accomplished, proper clamping must be considered to avoid premature tube line failure. When a line is left unsupported, mechanical vibration can shake the tube, causing fittings to loosen and leak (or the line to fail, in some instances).

Tube can be clamped individually or in sets, and can also be stacked. The most critical factor to any clamping system is having the correct number of clamps to achieve the proper result — that being a well-supported, vibration- and noise-free system.

Table 3 shows recommended spacing between clamps; Figure 4 shows an example. Clamp as close to each bend of the tube as possible (on both sides) to eliminate thrust in all directions.

Table 3

Table 3. Recommended tube clamp spacing.
Select figure to enlarge.

Figure 4

Figure 4. Optimal clamping configuration for tube support and vibration dampening.
Select figure to enlarge.


Quality of components
Approximately 15% of hydraulic system leakage can be traced back to poor component quality. It is essential to work with a reputable manufacturer that consistently provides high quality tube fittings that are made to SAE standards and that are dimensionally exact.

Taking time to identify quality components is the best way to avoid using inferior products. Generic “knock-off” fittings have become prevalent in recent years. If you suspect a manufacturer does not adhere to basic quality control measures, such as making fittings in only company owned and operated plants regardless of geographic location; or that parts are not machined to the highest standards; or that insufficient plating may lead to premature corrosion in the field; in these instances, do not risk the long-term reliability and overall safety of your hydraulic system to save a few dollars up front.

Furthermore, never use a fitting for which the type, size, working pressure and manufacturer is unknown. Many (though not all) fittings are stamped with identification marks. Establishing a supply of high quality fittings from a known reputable manufacturer is the best way to avoid this problem.

System abuse
System abuse, the final and most often overlooked factor (5% of the time) to hydraulic system leakage, can also be controlled. While this is typically assumed to be the responsibility of the end user, through proper system development the potential for abuse can be reduced. Besides adhering to the bending, routing and clamping best practices previously discussed, other considerations include:
1. Providing enough space (wrench clearance) to maintain equipment properly
2. Providing specialty tools to which the user normally would not have access (such as captive O-ring insertion tools)
3. Maintenance manuals outlining not only OEM and manufacturers’ part numbers but proper assembly techniques for servicing as well and,
4. Carefully considered routing that reduces the probability of users standing or climbing on tube lines.