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Youngman issues Boss X upgrade/recall

UK access specialist Youngman has issued an upgrade notice, following an incident with one of its micro scissor lifts at the end of October.

The incident involved a Youngman X3 being used by an employee of dry walling specialist BDL on a London site, after raising the platform to the desired working height, he released the control only to find that the machine continued to lift. Fortunately he was able to ‘scrunch down’ into the platform to avoid hitting the ceiling. His colleagues reacted quickly and used the lower controls to bring the platform down.

The machine’s owner Mr Plant Hire responded to a call out and found that the control solenoid contacts had stuck together, causing the motor to continue to run – pumping hydraulic oil into the lift cylinder until it was fully extended and blew the pressure relief valve. There were no obvious signs of damage or failure on the outside of the solenoid.

The contractor then issued a safety bulletin to its staff - which has been passed on to some other main contractors – informing its employees and sub-contractors of what occurred and warning them not to lean over the guardrails as they raised the platform, and to make sure that batteries are kept topped up – on the assumption that low voltage caused current spikes which caused the contacts to stick or fuse together.
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The original Youngman Boss X series

The rental company reported the incident to Youngman and its UK support dealer APS, the machine was stripped down and checked for any faults that might have caused the problem, none of which were found. The companies also failed to replicate the failure. The theory is that a drained battery resulting in a low voltage feed to the motor, caused a spike in the current to the solenoid which may have fused the contacts.

Boss X series scissor lifts built since January 2010 have been fitted with a low voltage cut-out device and since November 2012 they have also been equipped with two-way, normally-closed solenoid valves. Although the company failed to replicate the incident, it has taken the decision to issue retrofit upgrade kits to all owners of older Boss X series machines, adding the two way valve. In the meantime it is recommending that users maintain the batteries in a decent state of charge as a precaution.

We have now received a copy of the bulletin from Youngman which is being sent out today and publish it in full below. It will also be hosted in our on-line library. According to Youngman swapping the valve takes around 10 to 15 minutes and is a clean and easy job. The company expects to have enough kits in stock by the end of this week to cover all of the machines affected by this ‘recall’.

Vertikal Comment

While the reactions of the rental company, dealer and manufacturer looks to have been exemplary, especially when one learns what it has been doing in the six weeks or so since the incident occurred, there have been some shortcomings by the manufacturer in communications with owners.

Thankfully the contractor avoided the over-hyped wording that we saw in a couple of incident bulletins over the summer, where safety managers warned anyone who would listen to withdraw all of a manufacturer’s machines before it had checked if the event was a one off incident or not. However the manufacturer could have issued a warning to owners alerting them to the issue and what it was doing. Especially as the original BDL bulletin was circulating between some major contractors.

It is true that everything suggested that the risks were low, in that neither the rental company or dealer were able to replicate the failure, and if it had re-occurred, the platform is low enough that it was unlikely to reach many solid ceilings. It also lifts relatively slowly and it is unusual for the operator to lean over the guardrail of a scissor lift lifting.

However it does indicate that there is a need for a standard policy or guidance for the industry on how to handle such incidents and for an alert mechanism that avoids hype and overreaction.

December 2013

BoSS X2, BoSS X3, BoSS X3X

Youngman Group Ltd has become aware of a single and isolated incident where a BoSS X3 Micro Powered Access Platform continued to operate after the user released the platform raise button on the hand held controller.

A thorough examination of the incident unit suggests that the motor contactor points may have ‘stuck’ together, although this condition could not be replicated on the machine during testing. The most probable cause of this is excess heat at the contactor points, possibly attributable to excess current being drawn as a result of a measurable drop in battery voltage.

BoSS X-Series machines manufactured since January 2010 are fitted with low voltage protection, to prevent users inadvertently running the battery too low and, since November 2012 ‘two-way, normally closed’ solenoid operated valves have been fitted as standard. This latter component would have prevented the above condition whatever the cause of the contactors “sticking”.

Youngman Group regards safety as being of paramount importance and, to ensure there is no recurrence of this isolated event is making available upgrade kits, together with fitting instructions and any other assistance necessary, to all customers who purchased machines manufactured before November 2012. This upgrade kit includes the replacement of the ‘one-way, normally closed’ solenoid operated valve, which controls the ascent and descent functions of the platform, with a ‘two-way, normally closed’ solenoid operated valve.

Youngman Group has identified the serial numbers of all machines manufactured before November 2012 and is directly contacting those customers who purchased them.

In the meantime, as a precaution, it is recommended that batteries are kept charged, the charge indicator monitored regularly, and that machines are not used if the battery charge is less than 20% of full charge or, if it is likely that the battery charge will fall below 20% of full charge during the expected work period. In these instances the battery should be fully charged before use.

For more information on this matter, or for answers to any other queries you may have, please contact Youngman Customer Services on +44 (0)1621 745900.


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