* 2014 earnings forecast $3.10-$3.40/share vs est. $3.52
* Fourth-quarter revenue falls 15.8 pct to $1.73 bln
* Adjusted earnings $0.49/share, in line with estimate
* Sales at defense business falls about 46 pct
Oct 31 (Reuters) - Oshkosh Corp, a maker of specialty trucks, forecast 2014 earnings well below analysts' estimates after sales at the company's defense business plunged due to U.S. government spending cuts.
Oshkosh shares were down 7 percent in premarket trading, after it reported lower-than-expected revenue for the fourth quarter ended Sept. 30.
The company, which supplies medium and heavy tactical vehicles, gets about 45 percent of its revenue from the U.S. government.
Automatic budget cuts by the U.S. government, known as sequestration, have reduced spending by the defense department, hurting companies that supply equipment to the U.S. military.
The Pentagon's spending fell by $37 billion in 2013 and is likely to fall further by about $52 billion in 2014.
Boeing Co reported a 5 percent fall in sales of its military aircraft in the third quarter ended Sept. 30, while sales at General Dynamics Corp's combat systems business fell 30 percent.
Oshkosh forecast earnings of $3.10-$3.40 per share and revenue of $6.60 billion-$6.90 billion for the fiscal year ending September 2014.
Analysts on average were expecting profit of $3.52 per share and revenue of $6.72 billion, according to Thomson Reuters I/B/E/S.
Net income attributable to Oshkosh fell 54 percent to $36.3 million, or 40 cents per share, in the fourth quarter. Excluding items, the company earned 49 cents a share, in line with the average analyst estimate.
Sales at its defense business fell about 46 percent to $513.8 million.
Revenue from its access equipment business rose 8.9 percent, while that from its commercial business increased 15.4 percent.
Total revenue was down 15.8 percent at $1.73 billion, slightly below analysts' estimate of $1.75 billion.
Oshkosh shares were down at $49 before the bell.