page_title: CGR 4th Class 4-6-0TT 1880
section_title: Modifications
hierarchical_section_title: CGR 4th Class 4-6-0TT 1880 / Modifications
caption_attribution_description: English: John D. Tilney, Cape Government Railways (Eastern System) Locomotive Superintendent (1874-1904)
context_page_description: The Cape Government Railways 4th Class 4-6-0TT of 1880 was a South African steam locomotive from the pre-Union era in the Cape of Good Hope.
  In 1880 and 1881, the Cape Government Railways placed eighteen 4th Class 4-6-0 tank-and-tender locomotives in mainline service on its Midland and Eastern Systems, working out of Port Elizabeth and East London respectively. It was the first South African locomotive to be built to a local design. Four of these locomotives were still in service to come onto the South African Railways roster in 1912.
context_section_description: J.D. Tilney, the Eastern System's Locomotive Superintendent, carried out several experiments on some of these 4th Class locomotives. One of the modifications introduced by Tilney was an extended smokebox to make room for a very efficient spark arrester, constructed of wire mesh. In 1882, he reported that grass fires caused by locomotives had been rarely known since the spark-arresters were installed. Several locomotives on the Eastern and Midland Systems were altered to incorporate these spark arresters.
  Another modification involved modifying the boiler and frame to accommodate oscillating firebars and a larger firebox to overcome the problems associated with the low-grade local coal from the Cyphergat collieries. Mechanical firegrate shaking was accomplished by means of a collar on the leading coupled axle which could be engaged by a roller with eccentrically mounted connecting rods to the oscillating firebars. The drawings to illustrate the operation of the oscillating firebars were published in Mechanical Engineers in 1890.
caption: J.D. Tilney
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