07.07.2017

Do you have one of the six?

In May Niftylift published a Technical Bulletin, relating to a mandatory safety check and retro-fit of drain lines on HR12 4X4 boom lifts.

The vast majority of machines in service have now been retrofitted, BUT six remain and are proving to be difficult to trace. We ask that you check any machines you own or have on rent to see if you have one of these six – if you it should be taken out of service and the retrofit of a simple drain line carried out. If you have one of the machines, please contact Nifty Lift service manager Lee Casebrook who will immediately arrange a kit of parts or a service visit as appropriate. Telephone numbers +44 (0)1908 227460 or main number 223456

The serial numbers are:

12454: 2004
16531: 2007
16532: 2007
18798: 2009
19354: 2009
25256: 2013.

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The Nifty Lift HR12 4x4

The modification protects the gearbox from critical failure caused by a damaged drive shaft seal. The problem is caused by repeated shock loadings on the drive axle shafts, either from dropping of or smashing into high kerbs or dropping too rapidly when unloading with a crane. The knock on effect damages the drive shaft seal and causes excessive pressure spikes in the gearbox which can lead to a major failure.

The full text of the bulletin is as follows:

Technical Bulletin TB – 0120 : Issue 2

To : Machine owners as listed
From: Malcolm North
Date: 6thj May 2017
Our Ref TB- 0120_002
Re: Drive Gearbox Issues.

Mandatory Safety Check. - HR12 4x4 models
We have been made aware of a number of gearbox failures on HR12 4x4 machines.

Following extensive testing into the possible root cause, a mode of failure has been identified which is linked to internal mechanical damage of the wheel drive unit. This physical damage can be caused by inappropriate use of the machine which includes excessive kerbing and drop offs or the landing forces of a poorly controlled crane lift. In cases where damage is present in the wheel drive assembly, continued misuse during operation in high drive mode could lead to an internal failure of the wheel drive shaft seal, pressurising the gear box unit. This failure coupled with further improper use could in extreme cases, lead to the separation of the gearbox from the machine.
In order to mitigate the above serious failure mode, we are providing a modification that will protect the drive circuit in the event of internal wheel drive shaft seal damage.

The machine can then still suffer a damaged drive motor but the drain line will curtail the possibility of the internal pressure build up which leads to the critical failure when subjected to other external forces.

The instance of gearbox failure has been proven to occur shortly after the loss of the drive motor seal effectiveness, so any machine that is not displaying any evidence of oil leaks or loss of drive efficiency is still safe to use. Any machine that does have a characteristic of oil leaks from one of other of the drive motors must be taken out of service until it can be inspected and repaired. Under no circumstances should a machine be left in service with a damaged gearbox or drive motor.

The severity and risk associated with this potential issue has escalated this retro-fit to ‘Immediate Action’. Any machines that have yet to be fitted should be modified within the next four weeks from the date of this revision, after which they should be taken out of service until such time that the modification can be carried out.

Malcolm North
Engineering Manager.