DR Class 99.23-24

The series vehicles are 99.23 by Deutsche Reichsbahn procured meter gauge steam locomotives ( new locomotives). For the classification in the operating Park they got the car numbers 99231-99 247

History and technical details

For replacement of the partially outdated and moreover heterogeneous locomotive stock of the resin cross and Brocken Railway and the narrow gauge railway icefield - Schönbrunn, the German Reichsbahn procured 1954-1956 a total of 17 new locomotives. The design was derived from the Einheitsloks the DR series 99.22. The new locomotives, however, are all constructed of welded construction, they have instead of the bars of the frame Einheitsloks a welded sheet metal frame, a more complex drive construction and fully welded boiler with mixing preheater.

The first seven items ( 99231-99237 ) were originally equipped with two, each formed from the wheelset on each locomotive end and the adjacent Kuppelradsatz Krauss- Helmholtz steering racks. Due to problems with the sheet running one made in the machines of the second production batch but from the front wheelset and the first and second Kuppelradsatz triaxial Schwartzkopff Eckhardt steering racks. The locomotives of the first production series were reconstructed according to the early 1960s or in 1973/74 ( the last 99 7231 ). On the first weakened wheel flanges drive axles later was abandoned in favor of a better sheet run completely. As only the third, ie the Treibradsatz, and the fourth Kuppelradsatz are fixedly mounted in the locomotive frame, a wheel flange loose wheel but can not accept any cornering work, the locomotives have since been on no fixed wheelbase longer, but only a so-called run length which already Richard had been considered by Helmholtz, the developer of the Krauss- Helmholtz rack, theoretically as assigned accordingly.

The two-cylinder steam engine with simple steam expansion drives the third Kuppelradsatz as Treibradsatz; The locomotives have Heusingersteuerung Kuhn with shear loop and initially springless pressure compensation piston valves of the type Müller, later converted to Trofimoff slider.

The sheet metal frame used in place of the bars frame the standard design of new locomotives was not as robust as the former, it appeared from the start cracking and warping, which led to difficulties in the conversation. From 2004 to date were therefore seven locomotives ( 7232, 7240, 7245, 7239, 7236, 7241, 7234 ) equipped with a new, constructive revised sheet metal frame and new steam cylinders in welded construction. More to follow. All locomotives are still in the resin present, but partially inoperable and Z placed in smaller engine shed on the routes.

Following closure of the narrow gauge railway icefield - Schönbrunn, the new steam engines used there came to Lokeinsatzstelle Wernigerode. Due to the then existing large number of new locomotives in Wernigerode these were sometimes used on the Selketalbahn schedule. They unloaded on the Selketalbahn there the offset from the resin cross and Brockenbahn old Mallet locomotives.

All machines were different between 1976 and 1983 equipped with long oil firing and are the most powerful narrow gauge steam locomotives which have been used on German routes. With a favorable overall efficiency of around 5.5% it also among the most economical used in Germany narrow gauge locomotives. On trial runs, it was found that the mathematically defined as a boiler heating surface boundary of the executed without combustion chamber boiler of 55 kg / m² h without problems on 68 kg / m² h was increasing. Not in the long term to damage the boiler and the engine due to high load, the power boards only a heat flux of 60 kg / m were used as a basis but H; in this boiler limit a maximum effective power was at the hitch of 585 PSe at a speed of 15 km / h

The eight operational locomotives are today mainly on the Brocken in the Harz Railway and transport of Wernigerode ( six copies), Nordhausen (two copies) from used. Your car numbers varied from 99 231 et seq with the introduction of computer numbers 1970 99 7231 ff and after the installation of oil burning in 0231 99 ff HSB also continues to use the series scheme of the Deutsche Reichsbahn ( 1945-1993 ) in 1970.

Stock list

Gallery

Lok 99 7240 in Gernrode station ( Quedlinburg )

Lok 99 7237 in Wernigerode Lokeinsatzstelle

Lok 99 7240 in the Brocken Railway Station