Originally introduced by the Draconis Combine in 3067, the heavy-duty gyro is constructed from denser materials and features a reinforced outer shell, factors which allow it to withstand increased damage prior to failure. While apparently not of interest to the Clans, these attributes resulted in the technology's quick spread across the Inner Sphere during the maelstrom of the Jihad. However, while no more bulky than a standard gyro, the device is twice as heavy, resulting in a notable cost and weight penalty when used in conjunction with larger Fusion Engines. 
In game terms the heavy-duty gyro is able to withstand three critical hits, one more than standard gyro. The first hit results in a piloting skill roll penalty (+2 in Maximum Tech, +1 in Total Warfare) for rolls other than standard running or jumping movement, then suffers effects are normal. The heavy-duty gyro weighs twice as much as a standard gyro calculated on engine rating.  
- Tech Manual, pp. 219-220 "Gyros"
- Maximum Tech, p. 69 "Gyroscopes"