Hooves v Wheels

Despite the rise of the motor lorry, the horse remained almost unchallenged where heavy deliveries within a short radius were required. Brewers, coal merchants, the railway companies, etc. all relied on the horse. Not until the 1930's when Karrier and Scammell produced their respective 'mechanical horses' was the supremacy of the heavy horse threatened.

Karrier introduced their Cob 2-ton and Colt 4-ton three-wheeled prime-mover and trailers in conjunction with the L.M.S. railway powered by a Jowett, 7hp flat twin engine in 1931, which was upgraded with a larger Coventry Climax engine in 1933.

Scammell introduced their Mechanical Horses of 3-ton and 6-ton capacity in 1933, using the Scammell engine and Scammell automatic coupling gear which enabled the speedy changing of trailers. The Scammell M.H. was developed from the design bought from Napier.

Naturally this new means of urban deliveries attracted the attention of the trade press and various comparison tests were published in the early 1930's. One involved a Commercial Motor observer spending a day with the crew of a Scammell 3-tonner operated by a North London coal merchant, chosen for their mixed fleet of horse and machine.

The first thing the observer noted was the lively turn of speed, with 11mph being achieved when fully laden with 3 tons of coal. The first delivery was to a private house where thirty sacks of coal were tipped into the coal-hole at the end of a long sweeping driveway. The Scammell easily manoeuvred to within 4 feet of the hole while the driver remarked that the nearest the horse could get was the end of the driveway. This saved carrying the sacks seventy yards with obvious time saving. No mention was made about the saving in effort by the dray's crew.

A mix of residential and commercial addresses completed the round and the crew returned empty to base, achieving speeds up to 14mph. The trailer was quickly changed for a loaded one and the second round started. The pattern was thus set for a day's work of four rounds.

At the end of the day, the Scammell was re-fuelled with 3.5 gallons of ROP spirit and comparisons made between the work completed by both Scammell and a horse-drawn dray.

It was noted that the Scammell was able to achieve all the horse was able to and often exceeded the capability of the horse when room at the customer was tight. Turnaround times at the end of each round were quicker due to the speed of trailer change with the automatic coupling for the trailers.

Both Karrier and Scammell offered kits costing £30.0s.0d to convert horse drawn drays to use with mechanical horses.

In conclusion it was noted that the mechanical horse would cost £220.0s.0d per annum less to run than the number of horse-drawn drays needed to complete the same amount of work.


Work Completed

3-ton Scammell, two trailers & 2 men.
Horse, 2 drays & 2 men.
4 rounds at 6.5 miles each 3 rounds at 3 miles each
60 x 1cwt sacks per round 27 x 1 cwt sacks per round
Total weight per day = 12 tons Total weight per day = 4 ton 2cwt
Working hours = 8.5 per day Working hours = 8.5 per day
Average laden speed = 7.5mph Average laden speed = 2mph
Average unladen speed = 14mph Average unladen speed = 2mph

Running Costs per Annum
One Mechanical Horse, two trailers, driver and mate.

Fuel @ 1s 4d per gallon £54 19s 7d
Oil @ 5d per pint £5 7s 2d
Tyres (1 set lasting 2 years) £23 0s 0d
Maintenance £26 0s 0d
Licence £25 0s 0d
Driver's licence £0 5s 0d
Driver's wages @ £3 0s 0dper week £156 0s 0d
Mate's wages @ £2 10s 0dper week £130 0s 0d
Depreciation @ 20% £84 0s 0d
Garaging @ 4s per week £10 8s 0d
Insurance £12 0s 0d
Interest on capital @ 5% on £420 £21 0s 0d
Total £547 19s 0d

Three horses and drays @ daily hire charge of £2 15s 0d.
280 days per annum = £770 0s 0d.
(from the companies own records)

Difference = £222 1s 0d

The Scammell and Karrier proved to better the horse and Scammell went on to better Karrier, and later Jensen, continuing the concept through the 1950's with the Scarab and into the 1960's with the Townsman when front brake legislation ended the days of the 3-wheeled tractor unit.

Abridged from my original article in Vintage Roadscene, Vol 8, 30 (March-May 1992)