From Graces Guide
Priestman Brothers of Holderness Foundry, Hull.
Priestman Brothers was an engineering company based in Kingston upon Hull, that manufactured diggers, dredgers, cranes and other industrial machinery. In the late 1800s the company also produced the Priestman Oil Engine an early design of oil-fuelled internal combustion engine.
1872 By the time of Samuel's death, the business was in financial trouble.
1873 William went into partnership with his brother Samuel.
1876 The company's entry into the construction of dredging equipment began when they were asked to construct machinery to recover lost gold from the sea, west of the coast of Spain. No gold was found but the company's equipment proved useful for dredging of harbours and docks.
1883 Supplied two dockside steam cranes to Cockatoo Island Shipyard, Sydney. Both are currently unrestored at Fitzroy and Sutherland Docks. 
From 1888 to 1904 the company produced various versions of the Priestman Oil Engine, an early example of an internal combustion engine. Models were produced with engine power from 2 hp up to 60 hp for a double cylindered version.
1888 They were early developers of oil engines when they took the Eteve patent and with their own additions produced a practical motor 1885-92. It was exhibited at the Royal Agricultural Show at Nottingham in 1888.
1889 Formed limited company to take on the business of engineers, ironfounders, and engine builders in Hull and London. Shareholders were W. D. Priestman, S. Priestman, J, Priestman, Thomas Priestman, Edmund Priestman, A Priestman and Edgar Priestman. 
1892 The company opened a factory in Philadelphia (USA) in 1892, also producing engines.
1894 21 hp Oil Engine and Winding gear. Illustration and article. 
1894 Smithfield Club Show. Showed two engines. 
1894 Introduced a range of double-acting oil engines ranging from 30 to 65 hp 
1895 Bad debts and a decline in sales made the company insolvent, the business was reformed but William and Samuel lost their seats on the board. The business concentrated on cranes and grabs.
1900 Paris Exhibition. Description of the marine oil engines shown. 
1900 Company made public.
Post WWI: its products were used in the rebuilding of French villages, in 1921 a machine for digging field drainage drains was produced and the company received investment from the Ministry of Agriculture.
1928 production of excavators named after animals began; models named "Lion", "Tiger" and "Panther" were produced.
1950 The company constructed a factory in Marfleet, Hull, which eventually covered 63 acres
1961 Excavator, dredger and grab manufacturers. 1,000 employees. 
1968 Excavating machines. 
In the 1970s they developed a range of hydraulic excavators. The VC range of dredging machine with long reach booms to replace draglines. This had an innovative sliding counter weight to balance the boom at long reach. These were popular with small sand and gravel pits and with the drainage board and water companies in Lincolnshire for cleaning dykes. They also built special versions on tall pedestals for dock side unloading duties.
1984 Acrows was put into receivership. The Priestman division was sold off to the nearby firm of Sanderson of Skegness in Lincolnshire.
The Sanderson Group then got into trouble in the early 1990s and the Priestman operations were sold to another local company, RB Cranes, following the break up of the Ruston-Bucyrus group.
Today, what is left of the company trades in Bradford under new owner, Gardner Denver, the American based compressor and blower manufacturer. It no longer manufactures cranes or excavators.
The remains of a Priestman Bros steam dredger are stored at Swansea Museum Collection Centre (see photos). It is one of only three known survivors. The ingenious design has a minimum of moving parts. The drive from the crankshaft to the hoisting drum is by friction wheels. A large hand lever acts on the bearing supporting the wheel end of the drum shaft, so as to move the friction wheels into hard contact in one direction, and in the other direction to a non-driving position, and thence into contact with a fixed brake shoe below the large friction wheel - a fail-safe position. There is no provision for reversing the engine - the weight of the bucket and disengagement of the friction wheels obviate that need. A conventional arrangement of friction cones and bevel gears is used for slewing.
Sources of Information
- Chris Capewell, Queens Park London
- The Engineer of 15th March 1889 p235
- The Engineer of 21st June 1889 p522
- The Engineer of 20th June 1890 p496
- The Engineer of 14th December 1894 p524
- The Engineer of 6th July 1894 p5 & p9
- A-Z of British Stationary Engines by Patrick Knight. Published 1996. ISBN 1 873098 37 5
- The Engineer 1900/11/16 p487
- 1961 Dun and Bradstreet KBE
- The Engineer of 12th January 1968 p70
- The Times, Sep 05, 1984