For repeat visitors, I am adding more pictures and information as they become available:

Trevor Cheer - pictures of the frames of a Luke haulers (11th November 2019).

Paul Mahoney's potted history - https://teara.govt.nz/en/bush-trams-and-other-log-transport/page-1 great if you can't afford the out-of-print price for his classic book (11th November 2019). 

One book in my library which I do not consult too often is Paul Mahoney's "The Era of the Bush Tram in New Zealand", ISBN 0-908876-20-2. Most of it is taken up with the operation of the 'lokeys' on these very basic railways constructed to remove valuable timber. The extraction in itself was not particularly damaging in the environmental sense, but afterwards the land was often cleared and burned to create farmland.

If the 'Lokeys' are your prime interest this site is a 'must visit' - http://www.trainweb.org/nzgearedlocomotives/index.html.  

One key element in the operation was the use of steam log haulers. One of these, built at the Vulcan Foundry, Napier, is shown in this picture in the book (described as from the L.R. Young Collection) ready for delivery to a customer.

Phil Barnes takes up the story:

The machine pictured below is located at the Kauri Museum at Matakohe in Northland. The boiler was made by J J Niven of Napier and worked at 120psi, whilst the winching gear was made by The Whangarei Engineering Co. Its twin cylinders delivered 13½ hp which drive a twin winch system and this bit of the ‘apparatus’ was built in 1913. This machine worked in the forests of the central North Island and was last used in 1961, and was donated to the museum by Mr P Lacey from Taumaranui in the mid 1980s.

With the earlier steam driven log haulers, they only had a single wire rope which had to be taken to the log with a horse every time. By 1910, new twin winch haulers were on the scene with a thinner wire rope being taken to a block and tackle where the log was, then taken back to the machine where the 1” hauling rope was then drawn out to the log. When the log was drawn in (at speeds of up to 5mph), the thinner rope was returned to the hauler ready to draw the hauling rope out for the next log. Corners were negotiated using pulleys and careful manipulation!

The hauler its self was usually moved to the work site on a bush tramway and was anchored securely to counteract the pulling motion in the following way:- Its mounting runners butt up against a large transverse log which is secured by two props which are keyed into a ‘deadman’; a log buried under ground to form an anchor/foundation.

When operational these machines burned wood off cuts and could consume about 200 gallons of water per day. Communication was achieved by a long rope operating whistle, in order to tell the operator when to start and stop, a bit like a ship's telegraph.

Statistics say that between 500 and 600 steam powered log haulers were built by a variety of company’s and the last was used in 1969, although some can still be found around the country, mostly 'in the bush'.

Phil reports (7th November 2019) that he saw a Dispatch Foundry Log Hauler at Shantytown, near Greymouth on South Island's West Coast, housed in a replica of the company's building. Note that the old picture shows a rail mounted machine.

Elsewhere, I (RD) have found only one reference to a log hauler in another museum (Tokomaru, currently closed, 2019):

http://www.uniquelynz.com/tokomaru.htm  Tokomaru has two. 

Here are several more, some of which are still in the bush:

These are Wilson Lythgoe's pictures of a Dispatch Foundry hauler near Mumm's Sawmill on the Charming Creek system, now a popular hike.

Trevor Cheer has sent these pictures (11th November 2019) which show the frames of a Luke hauler (assumed steam) at Dinwoodie's tram near Erua, Makatote Tramway, the third picture, I am told, shows the remains of a 'skid'. For more information see these links:
https://www.flickr.com/photos/43338286@N05/10797551155  
https://www.heritage.org.nz/the-list/details/7668 

See also:
https://www.freewalks.nz/west-coast/charming-creek-railway-walk/track 
https://www.flickr.com/photos/84624351@N00/25226507483/ 

https://www.waymarking.com/waymarks/WM7RDY_Vintage_Steam_Log_Hauler_Pureora_Forest_New_Zealand

https://tramper.nz/6485/log-hauler/ (Link broken by September 2025)

https://blog.underoverarch.co.nz/2019/09/ 

https://www.geocaching.com/geocache/GC2HKV5_historic-sheridan-creek-otaki-forks-wellington?guid=a3ad72a5-6a51-4f27-b302-8bbc9781e22a 

https://www.flickr.com/photos/43338286@N05/5216849060/ Endean's sawmill, Waimiha, King Country

A full description of the operation of log haulers is available here:

https://www.pressreader.com/new-zealand/new-zealand-logger/20180424/282119227152881