Cylinder locking devices on backhoe stabiliser legs

Paul’s Post – the good oil from our chief techo

Cylinder locking devices on backhoe stabiliser legs?

I was recently asked to explain the application of the following Plant Assessor question to a backhoe loader inspection.

“Is this item of plant fitted with stabiliser legs, (answer N/A if not fitted), if so are hydraulic cylinder locking devices fitted to each to prevent movement in the event of hydraulic failure?”

The journey to this question appearing in Plant Assessor starts in AS1418, commonly known as “the crane standard” and finishes in the 2014 Guide for safe design of plant issued by Safe Work Australia.

In addition to these two important reference documents are many additional technical references that imply the need for these controls on stabiliser legs – however I’ll focus on these two today.

AS1418 Series

It is important to note that each section of AS1418 covers specific types of machinery e.g. AS1418.4 covers tower cranes, AS1418.5 covers mobile cranes, AS1418.16 covers concrete placing booms etc.

AS1418.1 specifies the general requirements for cranes, these requirements are applicable to all machines mentioned in any part of the AS1418 series unless there is a differing specific requirement contained in the individual parts of AS1418 for specific crane types.

AS1418.8 section 5 specifies the requirements for Earthmoving equipment when used to lift freely suspended loads. Backhoes are specifically mentioned the scope statement of this section:

5.1 GENERAL

Together with Section 1, the requirements of this Section shall apply when earthmoving equipment, including backhoes, front-end loaders, excavators, tool carriers and similar units are used for lifting freely suspended loads as secondary function associated with the normal applications of the equipment (e.g., lifting and moving pipes, unloading construction equipment, manoeuvring accessories associated with the equipment).

Section 5 does not contain a requirement for stabiliser legs to have cylinder locking devices however AS1418.1 clause 9.3.5 states the following:

9.3.5 Hydraulic circuits shall be designed and constructed, and the components adjusted, so that surge pressures remain within the allowable pressure limits of all a ected components of the system. The circuits shall incorporate the following safety features:

(a) Components accessible for easy and safe adjustment, maintenance and periodic testing.
(b) Safety devices to protect against the e ects of the failure of a hose in any support circuit on a crane…

Now remember that the requirements of AS1418.1 are applicable to backhoes as they are covered by a specific part of AS1418. Therefore this requirement is applicable to backhoes.
What if my backhoe can’t* be used as a crane I hear you ask? An excellent question and surely a genuine reason why AS1418 should not be applicable. This is where the Safe Work Australia guide is relevant.

* Plant Assessor defines this as having no lifting point therefore unable to lift a feely suspended load. It is fair to say that most backhoes have a lifting point fitted.

Safe Work Australia Guide for Safe Design of Plant

This document provides informative and practical guidance for people designing and redesigning plant & equipment. It contains the following statement regarding stability which is applicable to all machinery.

Stability
Unstable plant is a hazard. It can topple, parts can fall o or it can unexpectedly move and result in workers or others in the workplace su ering crushing or impact injuries. Designers should ensure plant is designed to be stable and without risk of overturning, falling or unexpected movement during erection or installation and under all operating conditions. It may be necessary for designers to consult with other stakeholders including manufacturers, erectors, installers and end users.

Stabiliser legs are fitted to a backhoe to provide a level platform for the machine to allow the backhoe boom and stick to move in a consistent plane while digging, dumping spoil or loading trucks etc. while on both level and non-level surfaces.

Sudden collapse of a supporting stabiliser leg may cause the backhoe to drop on that side, and this unexpected movement could result in:
•    workers in the area being struck by parts of the backhoe
•    the backhoe rolling onto workers in the area
•    the operator being injured from rollover of the backhoe

Therefore, in light of these and other references, and application of the risk assessment process, Plant Assessor applies the hydraulic cylinder locking devices question to backhoe loaders
As per usual, if you have any specific queries related to this or any other plant & equipment safety topic, please contact us.

Disclaimer: This information is intended to provide general information on the subject matter. This is not intended as legal or expert advice for your specific situation. You should seek professional advice before acting or relying on the content of this information. Please contact us for further assistance.

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