Directorate of Naval Recruiting

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HMS SULTAN has a Mini Sentinel

During HMS Sultan’s Summer Show 2005 Mr Markham brought along the mini sentinel and it proved to be an immediate hit with the younger children who wanted to play in it. The interest that was shown by the children proved to be good PR for HMS Sultan’s Steam Lorry and a lot of positive feedback was given.  However it was missing one vitakl ingredient – its own power!  A team of intrepid designers were given the task to motorise the mini Sentinel and ensure it mimics its big brother as closely as possible. 

The team decided to motorise the mini sentinel by using electric motors. The cost of motors ruled out buying new, so second hand ones were sourced via e-bay. Two motors were sourced and obtained from an old wheelchair both being 24V with 14.5 Amps of power.

 The team needed to have a way of controlling the speed of the Mini Sentinel. It was initially decided to use a Rheostat which would be ideal for the job, but when sourcing the item in the RS Catalogue it was found there were none. The RS Company were contacted and the technical staff informed us that Rheostats were not produced for use with such a high current of 14.5 Amps.  Therefore another solution had to be found to combat this problem.  For this a DCM – 24v dc motor controller module was used as it can handle up to 40 Amps and onto this a 53R cermet track pot was connected and used to control the speed. 

In order for the mini sentinel to be able to go in both the forward and reverse direction a simple three way position switch was used that gave the option of forward, reverse and neutral. 

To enable the mini sentinel to have working lights they researched how they would be connected up and how to make them look the same as the full sized Super Sentinel. A Haynes manual was used to help with wiring up a simple car lighting circuit. The indicators were brought as a kit as they were a bit harder to wire up. Photos were taken of the main Steam Lorry and these were compared with lights that were available through local purchase. 

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