AKA Cambridge carrier

[Jon Bradshaw]

To answer your question- Does the image Jon posted of the driver hand and foot controls show a third foot pedal to the left . . . a gear change pedal (GCP)?
--Yes there is a third pedal down at the left beside the final drive and it is attached into the side of the center gearbox. I do not know what it does, it may have been a carry over from other design and do nothing or it may be a gear change lever. I will need to take a closer look when the weather is warm again.
You also mention cletrac steering with dual tillers, do you have some insight into what final drive assembly this is? A "normal" final drive (like a T16) doesn't have a transmission style shifter built into it with 5 gears and a reverse lever.....
This makes me wonder if the transmission is almost superfluous and the final drive can act as the transmission? Or it is geared in such a way as to allow massively low and high gearing (might be why the 5th gear is locked out with a bolt) 5th and 5th would be really fast. 1st and 1st would climb almost any hill with a load under tow. The reverse lever would act like a ferret and give you the same 5+5 in reverse....

[Richard Farrant]

Originally Posted by Jon Bradshaw

--Yes there is a third pedal down at the left beside the final drive and it is attached into the side of the center gearbox. I do not know what it does, it may have been a carry over from other design and do nothing or it may be a gear change lever. I will need to take a closer look when the weather is warm again.
You also mention cletrac steering with dual tillers, do you have some insight into what final drive assembly this is? A "normal" final drive (like a T16) doesn't have a transmission style shifter built into it with 5 gears and a reverse lever.....
This makes me wonder if the transmission is almost superfluous and the final drive can act as the transmission? Or it is geared in such a way as to allow massively low and high gearing (might be why the 5th gear is locked out with a bolt) 5th and 5th would be really fast. 1st and 1st would climb almost any hill with a load under tow. The reverse lever would act like a ferret and give you the same 5+5 in reverse....

Hi Jon,
The left pedal will be connected to the pre-selector gearbox by rods and operate a lever on the top side of the box, this works the busbar in order to engage a pre-selected gear. No different to a Ferret which you may be familiar with. The driver operated gear selector gate appears to only be mounted on the front steering/ forward and reverse casing and I can see the outside lever, this will in turn, by rods, operate the small lever on the side of the pre-select gearbox.

regards, Richard

[David Herbert]

This FV402 has a steering system that functions exactly the same as that in a T16. There is a Cletrac controlled differential with contracting band brakes running in oil in the central unit to provide the main steering function which when an outer steering lever is applied. this reduces the speed of one track and at the same time speeds up the other track by the same amount. A full application of one of these brakes will make one track go at about half the speed of the other with less difference / bigger radius of turn if you partially apply the brake.

Just inside the lower hull sides and mounted onto the final drive units are drum brakes with rod linkages to the stopping brake pedal and to the two central steering levers. Thus these brakes can be used either as the service brake (for slowing down / stopping) as a parking brake by pulling and latching the two centre steering levers, or for pivot turns in very confined situations by pulling just one centre steering lever.

Also inside the steering gearbox is the forward / reverse gearbox. This can only be changed with the vehicle stationary and the Wilson box in neutral. There is a neutral position in the F/R box but it is very unwise to try to engage F or R from N with the engine running - even with the Wilson box in neutral. There is too much drag in the Wildon box so the prop shaft etc will turn at about engine speed and the resultant grinding of gears in the F/R box is very destructive. Instead, stop, engage N in the Wilson box (or GC pedal to the floor which is what N position is) and smartly but not violently go straight from F to R or the other way. Do not pause in N or the propshaft will spin up.

The Wilson box contains 5 possible gears that can be engaged at any speed or load by pre selecting what you want next and then fully pressing and releasing the GC pedal. Do not use this as a clutch, but release it smartly in one movement. There is a fluid flywheel between the engine and Wilson box to cushion the drive and allow stopping in gear and progressive engement of the drive when starting off. When changing up or down match the engine revs to the next gear as you would with a manual box.

Unlike a T16 you are not supposed to use the Cletrac (outer steering levers) both together to stop the vehicle and there may well be an interlock to prevent you. This is a hangover from WW2 British tank designs as the Merrit Brown box in Cromwells etc would be damaged if you engaged both steering brakes.

This four lever system continued through the FV420 series into the pre production FV432s but then someone realised it was silly and production FV430 series got an ordinary Cletrac system with a more robust Cletrac controlled differential and no separate stopping brakes. This lasted untill modern civilian legislation required the FV430 series to be upgraded with a steering box that offered two separate braking systems.

David

[Michael R.]

I imagine your research quiry at The Tank Museum, Bovington, and to some extent other information sources as necessary, such as IWM, CWM and LAC may indicated your carrier is one of the Pilot models.

Are there a total of three (3) FV402 pilot models, or more? The Tank Museum, Bovington appears to hold FVPE 3818.

Two other known AOP No.4 FV402 series are:
FVPE 3816, Pilot model 1, UK Registration JXW 32
FVPE 3903, Pilot model 2, UK Registration KYW 36




IWM: Imperial War Museum, London
CWM: Canadian War Museum, Ottawa
LAC: Library and Archives Canada, Ottawa

[Jon Bradshaw]

The researcher said that they have Mark 1- FV402 Armoured Observation Post No. 4 Mark 1 and the registration number for it is 60 BA 09. I am still waiting on more info from them but it raised a question in my mind about numbers. It is the one in the pics FVPE 3818.
Since the earlier pictures I had seen of this vehicle (attached) had the UXM 65 number on it and that was the same as the number on a target hull pic I also have seen (but can't find right now). I wonder if it was taken off the range and given a new number/ brought onto charge in the military just for the museum?

Quote from- Michael R- Two other known AOP No.4 FV402 series are:
FVPE 3816, Pilot model 1, UK Registration JXW 32
FVPE 3903, Pilot model 2, UK Registration KYW 36
Are you saying there are two other carriers out there in museum/private collections?

The pic is from the old thread on this site about this carrier from 2005. A few more pics as good as these and I would have enough to start getting a fabrication plan together. I still have no idea what the inside would look like. Other than the drivers seat, it was completely stripped out.

Interesting the amount of dust collected on it over the years. I assume the new vehicle preservation building is much more "dust free" then the old one.
Picture is courtesy of Dennis Trowbridge, see http://community.webshots.com/user/jtrowbridge5

[David Herbert]

Pilot vehicles would normally have had civilian style registration numbers like UXM65. They also usually had a large P1, P2 etc in white painted on in obvious places for easy recognition. These were used for basic development of the design.
Pre production vehicles usually had army registrations like 60BA09 and a large W1, W2 etc. These were built for troop trials but often had major modifications as the trials went along.
Series production vehicles would have army numbers.
FVRDE / FVPE numbers were allocated to all individual vehicles being developed or tested by those organisations. They were painted on any obvious flatish surface, often on the front and were often refered to as 'wing numbers' as they would be painted on a front wing (fender) of a wheeled vehicle.

David

[Jon Bradshaw]

The researcher has replied to me that she has found quite a bunch of info on the carrier FV 401/ armoured OP FV 402 and wants to know what I would like her to send me....
The list of stuff is long but it is excerpts from different books and some manuals she found. Without seeing what she has I am stuck, I guess I will just order it all and sort out whats good when it arrives.

The list of the items she found are-

Outline and Transport Diagrams, Plate Thickness, Suspension and Engine and Transmission (6 pages)

Carrier, Armoured, O.P., No. 4, FV 402 (photograph and basic description)(1 page)

Provisional User Handbook (for troop trials) for Carrier, Universal No.4 (FV401) and Carrier, A.O.P, No. 4 (FV402), WO Code 17767
(basic description of contents: General Description, User Servicing and Adjustments, Fault Finding Charts, Appendix and List of Illustrations: 34 figures) (88 pages)

Ministry of Supply, Fighting Vehicles Proving Establishment, Report No. F.T.2007, Cambridge Carrier Development Trials (20 pages of text, 2 pages of graphs, 6 pages of photographs)

Ministry of Supply, Fighting Vehicles Proving Establishment, Report No. F.T.1908, Development Trials: F.V.402 Prototype No. 1. (First 1000 Miles), 10th Nov 1950 (20 pages of text, 3 pages of graphs, 2 pages of photographs

Universal Carriers, Volume 2’ by Nigel Watson (Choir Press, 2006)
(This chapter covers the FV402 and FV401. There is a brief description, stowage sketches, interiors, wading device information, dimensions. Photos throughout. (19 pages- pp.234-252)


I have been looking for the book Universal Carriers, Volume 2’ by Nigel Watson. Amazon and Ebay and a bunch of other sites are all out of stock. Does anyone have this book and are you willing to part with it? If not then I will buy the pages particular to this carrier from the museum.....