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Mack/Baker Aerialscope

BY: Dave Lott, PHOTOGRAPHY BY: Dave Lott/supplied

Date: 20.12.2012


When we started to build upwards, the need for fire fighters to have an alternative means of accessing the upper floors of buildings, besides the internal stairs, became essential. The first and best climbing tool ever made was the simple ladder, so it was natural we would grab these to gain entry into tall buildings when they were on fire.

Mack/Baker Aerialscope
Mack/Baker Aerialscope

A Brief History of Aerial Appliances

As our buildings developed and grew higher, so did the humble ladder. But with added-height came extra weight, and so wheels were attached to larger ladders to make them easier to manhandle. With the introduction of automobiles in the early 20th Century, the next progression was to carry these large ladders on vehicles.

Doing so had a two-fold effect: firstly the ladder could be made stronger and heavier, to reach even higher. Secondly it could now arrive at a fire much quicker.

Once ladders were installed onto the chassis, outriggers were added, and the truck then became a very stable base and even greater heights could be achieved. Ladder truck evolution continued this way until 1958 when something revolutionary occurred in Chicago, Illinois.

Robert Quinn, the Fire Commissioner of Chicago, was driving to work one day and noticed workers using a cherry picker to trim trees and wash and repair signs. He had a radical thought. Chicago had been looking for a replacement vehicle for some of their aging water tower trucks and this, he decided, could be the answer. Quinn got together with other department heads and after discussing the idea, they made contact with the Pitman Manufacturing Company in Missouri and challenged them with building a unit that would work for the fire service.

The result was a 50ft snorkel type unit; mounted on a GMC chassis. This simply-engineered unit was delivered to the Chicago Fire Department in September 1958.

The Aerialscope

Elevated platforms continued to develop and grow in number through to the mid-Sixties, when again things changed. The Fire Department of New York (FDNY) had been looking for an aerial appliance that could cope with the special conditions found in the sprawling city. These included cold winters, narrow streets with cars parked on either side and with buildings set back from the road, usually under six stories in height. They let their interest be known to all fire truck builders, who all knew the FDNY would place a large order for the right vehicle.

In 1964 Mack trucks engineered a brand-new product in response to the request from FDNY. Mack contracted a company called Eaton Metal to build the first Aerialscope. The original unit had the cylinder and water system inside the enclosed boom. They were offered on a Mack C-model chassis with gasoline engines, but once the CF chassis was introduced, they were all powered by diesel engines instead.

Mack then found a manufacturer called Baker Equipment Engineering that was building telescopic equipment for Boeing, in addition to making bucket trucks. Mack contracted with Baker to build the Aerialscope; a partnership which continued for many decades. Both companies designed their respective product to be uniquely paired with that of the other. Raw Mack CF chassis' were assembled and sent to Baker for installation of the Aerialscope, outriggers, body and everything else needed to make it a fire appliance. The truck would then be returned to Mack for painting and finishing touches.

Mack handled all the marketing and distribution, while Baker assumed all of the marketing of the Aerialscope specifically, while still in an exclusive agreement with Mack to provide the chassis and service support.

The Aerialscope is different to other aerials in that it utilises a single pair of outriggers for stabilisation. It also has four vertical jacks, one on each corner to help lift the vehicle off the ground. Most other aerials use two pairs of outriggers. Having a single pair is an advantage when the unit has to set up on a narrow, congested street: the outriggers can be lowered between two parked cars. As the corner jacks only lower down vertically, there are no other setup concerns or considerations (vehicles with four outriggers required more space around them, which is sometimes hard to find close to the fire).

The CF chassis Mack produced was specifically designed to accommodate the Aerialscope and as such allowed Baker to install the scope directly to the frame, instead of to a sub-frame or structural box. This made the entire unit sturdier and more durable. It also allowed the Aerialscope to sit lower on the chassis so the overall height of the vehicle is lower than a standard aerial appliance.

The telescoping boom is totally enclosed. This means it won't freeze up like ladders can in cold conditions. The first section of the boom is steel, with the remaining three made from aluminium. The telescoping design permits it to deploy in any direction with a minimum of movement, and makes positioning the scope easier than a typical multi-jointed snorkel. The basket also boasts a huge weight capacity: 1000 pounds (450kg) in any position at any angle, even with water flowing.

In 1990 Mack stopped producing its custom CF chassis following a decision to cease manufacturing fire trucks altogether. Baker had been given six months notice and they found a replacement with another supplier, Simon-Duplex.

The first non-Mack Aerialscope was built in 1991. The following year Spartan designed a chassis that would accommodate the Baker Aerialscope. There were now two choices for buyers, plus a new 95ft version. This was achieved by adding five feet to each boom section. The fold down stabilisers had to increase in size, however as a result the weight increased significantly too, to around 37-tonnes.

In the early Nineties the FDNY – the biggest Aerialscope user by far – started using Seagrave as its main supplier of fire appliances; both pumping and aerial units. They also wanted their new Aerialscopes' to be mounted on Seagrave chassis' to maintain uniformity throughout their fleet. They encouraged both Seagrave and Baker to make it happen. Seagrave already had a heavy-duty chassis that was easily made to accept the Aerialscope. From then on Seagrave became the primary chassis supplier.

Meanwhile, by 1996 Baker Equipment Engineering was facing financial problems and went into bankruptcy. Seagrave's parent company purchased the Aerialscope rights and continued manufacturing units under a separate company. Since then the 95ft Aerialscope II has been engineered and is available, alongside the original but modernised 75ft Aerialscope II.

Over 350 CF Mack Aerialscopes were produced, but only a very small percentage had pumps installed. Since 1964, 172 have gone to the FDNY, including the last one ever produced in December 1990. There can be over 70 Aerialscopes stationed throughout New York at any one time.

All the Aerialscopes ever made were for the US market, with only a handful of exceptions. Around five were exported to Canada, while a single unit was shipped to a little nation in the South Pacific called New Zealand.

The New Zealand Aerialscope Story

In 1971 the Auckland Metropolitan Fire Brigade (AMFB) took delivery of a brand new International Snorkel with a Cincinnati cab. It had a working height of 65ft.

This four-man appliance had a Darley SH1250 centrally-mounted pump and proved to be an excellent choice for the developing city. But Auckland was growing fast and by the end of the '70s the Snorkel was in need of replacement. Meanwhile, in 1975 the New Zealand Fire Commission had been introduced and the country had, for the first time, a truly national fire service; the New Zealand Fire Service (NZFS).

While most countries have provincial fire brigades, the NZFS is one of only a handful of national fire brigades found anywhere in the world. The replacement decision on Auckland's Snorkel would now have to be made by the Commission in Wellington.

With the need identified, a tender was issued for three Hydraulically Elevated Platform (HEP) appliances. One was for Auckland and two for other provincial cities. One of the tenders' received was from Ron Carpenter's Motor Truck Distributors (MTD) in Palmerston North; then and now the Mack truck distributor for New Zealand.

Their offer was for a 75ft Baker Aerialscope, mounted on a Mack CF612 chassis with a 320bhp diesel Mack Thermodyne and Mack Dynatard engine brake. The gearbox option was an Allison HT 740 four-speed automatic. This was to be fitted with a Darley SH1500 pump and two High Pressure Deliveries (HPD's).

Simon (UK) and Pitman (USA) basket appliance offers were also received, but the Aerialscope's specifications in working height, field of operations, basket loading, and pumping capacity were superior to any other solution the NZFS was offered.

With a clear winner, the Operations Division then recommended the purchase of the Aerialscope to the Tenders Committee, which they in turn supported. This was based on the heavy workload being experienced in the rapidly-growing city of Auckland.

However, the Tenders Committee were not at all confident the Commission would approve such a request. The Aerialscope appliance was going to be very large, unique to Australasia and certainly not cheap. No one knows for sure, but it was suggested that there wouldn't be much change from a million dollars for the rig. And remember this was 1980, when most fire trucks cost around $120,000.

The Fire Commissioner at that time was Frank Hardy. Hardy had recently returned from an extensive trip to England and the United States, during which he also looked at modern aerial appliances in both countries. While on the east coast of America he witnessed the FDNY Aerialscopes in action, and was impressed with their ruggedness. These trucks would tackle large working fires almost on a daily basis and, as Hardy reasoned, if they can survive the harsh New York environment, one could surely survive in Auckland.

Hardy also had the unfortunate experience of being in the basket of a particular 150ft aerial when one of its outriggers failed. That vehicle was never included in the tender bid, although the experience must have reinforced to Hardy the importance of purchasing a robust, well-engineered appliance.

It would be an understatement to say the Tenders Committee was stunned when the Commission announced the acceptance of the Aerialscope bid. But unbeknown to them, the Commission's approval of the Aerialscope was virtually a given. Hardy had already convinced Sir Jack Hunn (chairman) and fellow commissioner Bill Henderson that this aerial would be ideal for Auckland. He knew this is where the major fire and rescue activity was and the Commission, who would make the ultimate decision, was already on board.

Hardy was totally pro-Auckland and there was no question that the Aerialscope would definitely head there. Interestingly, it is almost certain the AMFB would not have approved such an expensive purchase. Auckland Fire Region heads were contacted and agreed to accept the appliance once built.

Auckland Fire Region Commander Allan Bruce then travelled across America on a fact-finding tour. He was the coordinator with Hardy on the procurement of the truck and visited the Mack factory in Allentown, Pennsylvania, where the Kiwi vehicle was being built. He had also seen three Aerialscopes' attack a large fire in New York and believed it was what Auckland needed. Hardy wanted to introduce an Aerialscope into New Zealand to test the potential for future purchases.

The appliance would have a large pump and large aerial combination, and extensive work went into the design to ensure both elements would work to their maximum capabilities'. The design of the body was kept clean, simple and functional, as was the pipe-work for the water.

The chassis was assembled by Mack in Palmerston North and driven to Rotorua where Mills Tui assembled and installed the Baker Aerialscope and Darley pump. Oversize tyres were fitted to the front wheels to comply with the Ministry of Transport weight exemption on the front axle, while Ian Kerr of Mills Tui oversaw the original paintwork.

It is the only Aerialscope in the Southern Hemisphere and the only one ever fitted with a Darley pump. It's also the only right-hand drive model ever produced in the world.

One area of concern was how to supply the pump with such a large amount of water. The NZFS use 90mm feeder hoses to move water from fire hydrants to fire trucks, but the Aerialscope could produce over 5600-litres-per-minute; almost twice the amount of a normal fire appliance.

The solution was a wheel-shaped portable water-collector called a Maverick. Six feeder hoses could be connected simultaneously and this combined water would then be funnelled down a long 150mm diameter hose, known as a Storz hose, directly into the pump. Using this hose (which is the largest hose in use by the NZFS), the Aerialscope could now be supplied with the water needed to keep all of its six 70mm outlet hose deliveries and two HPD's working at full capacity; not to mention the two individually-operated monitors in the basket, each capable of putting out 38-litres-per-second on their own.

Combined, that's over 4.5-tonnes of water-per-minute; a truly incredible amount of water and the most any NZFS appliance can produce. It's fair to say that many a fire has met its match once the big Aerialscope arrives on the fire ground.

Fire appliances tend to have low mileage. On average, most trips would be less than 5km each way. The vehicle will be driven hard and at speed, but usually not very far. However, unlike normal trucks, fire appliances sit at full weight, 24 hours a day, and can expect hard acceleration and braking from the get go. The parts that take the most hammering in any fire appliance are the springs, centre bolts, brakes and tyres; the Aerialscope is no different. The engine also drives the water pump, so it can be working when the truck isn't moving, yet the speedometer will still be increasing.

Because fire trucks can depart at any time of the day, they have a 230V electric wire plugged into them to heat the engine water using an element about the size of a household kettle. The warm water in turn keeps the engine oil warm. Onboard battery chargers keep the truck batteries charging at about two amps. The wire automatically unplugs as the truck drives out the door.

Changes and repairs

One of the first changes to be made to the Aerialscope came as a result of the Auckland's topography. There are over 40 volcanos in the region and, as a result, many steep hills. With the chassis design based on examples from the FDNY, which work on mostly flat terrain, the steep hills of Auckland proved to be a problem.

The frame overhangs 4.5m behind the rear axle, and this would bottom-out the truck when steeper streets were encountered; especially City Road in the CBD. The appliance would find itself wedged between the front wheels and the rear frame, with the drive wheels spinning freely in the air. After a few mishaps a decision was made to trim some of the rear locker space on an upward angle from the rear access ladder; a modification that can still be seen today. Even with this improvement though, Aerialscope drivers' still need to take care driving down very steep slopes around Auckland.

After many repairs, the chrome front bumper was finally damaged beyond repair after a car collided with the appliance. An aluminium replacement was manufactured, and a red beacon was installed on this. The unique oscillating red MARS light developed a conducting earth problem and eventually had to be removed.

The Aerialscope has had three total refurbishments. The first was in the late-1980s, followed by another in the mid-1990s, with the most recent refurb beginning on January 12, 2001, after it was noticed the appliance's third and last extending section had a pronounced droop: one can only imagine how this occurred.

All three extending sections were replaced with brand new units. Cracks were discovered in the basket and it was stripped down and rebuilt to the latest manufacturer's specifications. The escape ladder was also replaced with a non-conducting model. The original ladder was the electrical earth for the basket, so a new earth had to be installed to comply with current regulations. The third refurbishment was the biggest to date, with items like the slew ring ball bearings, wear pads, hydraulic control valves and electrical cables all replaced.

During the first refurbishment, when an agent was servicing the large hydraulic rams, the boom was lowered but only one ram closed. The resulting twisting movement caused serious damage to the turntable, and it had to be repaired.

The engine has been rebuilt twice; both times due to a broken camshaft. The turntable, meanwhile, was replaced around 1990 due to continuing problems with the rotation bearings (slew ring). The replacement base had a new non-slip surface, where the original did not.

The rear suspension has been refurbished around six or seven times too, simply due to the vehicles' length, weight and general wear and tear associated with this unique rig. It came supplied with heavy-duty springs, yet lightweight differentials. This unusual match came straight from the factory in America and had been the cause of some mystification ever since its arrival in New Zealand.

Sometime around 2006, the four corner jacks had their footplates upgraded to the latest design after the original ball-style had finally worn out. Rubber pads were also installed to stop the plates rattling when in the transport position.

A few years ago, the rear trunnion pin broke when the truck was being reversed into city station, causing damage to the bodywork. The incident happened in the late afternoon and it subsequently took around five hours to move the truck from city station to the workshop. If this had failed minutes earlier, when the appliance was responding to a fire call, the Aerialscope most likely would have rolled. The trunnion pin was found to be hollow so a new, solid replacement pin was engineered.

The Aerialscope's Future

At this stage the future of the Aerialscope is uncertain but it would indubitably be a major loss to the city (and fire buffs the world over), if this fine machine were not preserved for historical significance. The rig has been a vital part of Auckland's urban heritage for 32 years and, as mentioned earlier, is the only one of its kind in the world.

Aerials are designed to put large amounts of water onto a fire, and the best aerial in New Zealand for doing this is the Aerialscope; call sign 'Auckland 205', based at city station.

The courageous move to purchase such a unique vehicle back in 1980 has shown itself, time and again, to have been a masterstroke by those involved.

Special thanks to Dave Lott for co-ordinating all the information from many different sources and assisting in the production of the Aerialscope articles. Dave is an operational firefighter based in Auckland City Central District. Ironically, he is not Aerialscope qualified

– Randolph Covich, Editor

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