What follows are the basic details of the patent application for the Opperman Motocart complete with original specification drawings.
The original design of the Opperman Motocart aimed to provide ‘a vehicle of simple and cheap construction which would be suitable for the transport or delivery of goods for example or if desired for agricultural purposes and having a driving unit including a single front driving wheel supported by an upswept part of the vehicle frame’.
The patent application was filed under ‘improvements for motor vehicles’ and submitted by Stanley Edward Opperman of Greenhill, Ganwick Corner, near Barnet, Hertfordshire and Ganwick Estates Ltd. of Norwich House, 13 Southampton Place, London, W.C.1. on July 29th 1946. Application number GB2250846A.
|4||lattice girders – rear frame|
|7||upswept forward portion|
|7a||bracket for alternative siting of steering box|
|8||front, driven wheel|
|9||vertical bearing housing|
|11||depending rod or tube|
|14||shaft, steering column|
|16||platform to carry motor and gearbox|
|17||power source, engine|
|19||drive chain cover|
|20||flexible wire, throttle cable|
Referring to figure 1 above, it can be seen that the rear frame was to be comprised of a pair of spaced lattice girders (no. 4), here fitted with a simple agricultural body (no. 5) but other bodies could be fitted to suit the application. The small road wheels (no 6) could be mounted on a common axle or be mounted on individual stub axles. It was envisaged that any desired arrangement of suspension, for example half-elliptical springs could be used.
Looking at figures 1 & 2, at the front it can be seen that the lattice girders of the rear frame are connected to the upswept, forward portion (no 7). It was stated that the upswept forward portion could be fabricated from sheet metal or light alloy panels and was designed to clear the front wheel and provide a seat for the driver.
A vertical bearing housing (no 9) housed a spindle fitted with lateral arms (no 10) situated above and below the bearing housing. These lateral arms are attached to a depending rod or tube (no 11) to which the power unit (A) is attached. It was suggested that the depending rod could be fabricated in sheet metal and welded.
Referring to figures 1, 2 & 3. To allow steering of the road wheel (no. 8) any common type of steering box used in motor vehicles could be used (no. 12). It would be mounted above the vertical bearing housing (no. 9) on the upswept frame (no. 7). As an alternative location a bracket (no. 7a) was also suggested.
The steering arm (no. 13) that comes from the steering box, engages with lugs on the top end of the vertical rod (no. 11). From the rear of the steering box a shaft (steering column) (no. 14) carries the steering wheel (no. 15).
Power Unit and Gearbox
Referring to figures 1, 2 & 3 it can be seen that a platform is provided (no. 16) to which the power source is fixed (no. 17). A suggested power unit was an air cooled, internal combustion engine. In addition to the power unit, a gear box (no. 18 fig. 3) is also mounted on the platform. This could take the form of a simple four speed and reverse box driven by a chain from the engine. (No.19, fig. 2) shows the chain cover.
The gear box has a pinion which meshes with a spur gear wheel on the axis of the road wheel (no. 8). Suitable bearings, either roller or ball bearings were journaled on a stub axle (dotted line 19a in fig. 3) which projects laterally from the vertical rod or tube (no. 11).
It was proposed that front suspension could be provided by fitting a helical spring within the vertical tube (no. 11).
To operate the engine, a control lever, fitted to a suitable position such as the steering shaft (no. 14), operates a flexible wire or throttle cable (no. 20, fig. 1). A clutch and foot brake were to be fitted between the sides of the frame (no. 7) to allow easy access for the operator. A handbrake (no. 22, fig. 1) may be fitted. The brakes, of standard drum brake design, could operate on just the rear wheels, the drive wheel or both. A gear lever (no. 21) is to be fitted directly on to the gearbox (no. 18, fig. 1).
It was suggested that the rear body could be adapted to be tipped allowing easy discharge of its contents by incorporating a suitable tipping mechanism. All wheels were to be of the usual detachable type, fitted with pneumatic or other tyres.
Special thanks go to Mark Dudfield who very kindly sent in the photo of his beautiful, restored Opperman Motocart and gave permission for the use of the image. It was also Mark who gave me the idea for this article, so many thanks Mark!
If you would like to see more great photos and learn more about the Opperman Motocart and some of the other products they produced, like the Opperman Scorpion Mark 1 check out Marks – Opperman Club Facebook page at https://www.facebook.com/groups/118221101593055/
To view my other articles please visit https://farmingthroughtheages.com/
I hope you have found this article interesting and welcome any comments.
Thank you – Justin