WALTHAM -- Fire Chief Thomas Keough received a $318,000 special delivery yesterday.

The newest engine in the fleet, Engine 7, arrived at Fire Department headquarters on Lexington Street, replacing its 21-year-old predecessor. According to Keough, the new engine will be stationed at the Lake Street firehouse.

Keough said the upgrade was needed to maintain service levels and ensure firefighter and public safety.

"What you perceive as bells and whistles, those are the things that get us where we want to go as quickly as possible," said Keough. "This truck is a tool and our firefighters can only work as well as the tools they are provided with.

"It may look pretty, but this is an effective and powerful piece of machinery," said Keough outside the station yesterday.

The engine was constructed by Greenwood Fire Apparatus Inc., a North Attleboro company. The aluminum body of the fire truck, along with the enclosed cabin where firefighters sit, are some improvements that make newer engines safer for emergency workers, a Greenwood representative said.

"This is the safest cabin in the industry," said Walter Cryan, vice president of Customer Relations and Community Affairs. Cryan was at fire headquarters yesterday to deliver the several-ton engine.

"We put technology to work for safety sake," Cryan said.

Besides a 330-horsepower engine, the new truck boasts a 750-gallon water tank, a 30-gallon foam tank and has the capability to pump 1,200 gallons per minute.

Six firefighters can fit inside the cabin, which also has its own unique ventilation system that can slowly cool firefighters in the summertime and warm them in the winter.

"The heating and cooling systems are needed for rehab purposes," said Keough. "Say we have firefighters out on a 95-degree day, they can come into the cabin and start the process of cooling down their bodies slowly."

Even the seats of the engine are specialized. Firefighters can connect oxygen tanks to their firefighting suits en route to an emergency, rather than attaching the tanks at the scene like they do now.

"There really is no comparison between the old and the new engines," said Keough. "One was built in 1983 with 1983 technology. This engine is brand new with all the newest technologies."

According to the chief, not everything is new, however. The lettering on the front and sides on the state-of-the-art engine is an exact replica of the 1871 Waltham hose wagon that currently sits in a museum in Maine.

"The vehicle may be new, but there is an element of heritage on this truck," said Keough. "It's important for us to maintain that heritage."