An undercarriage for heavy diagnostic equipment having a selectably engageable swivel mechanism activated by the movement of a cam to allow the undercarriage to be turned when desired and rolled in a straight line when necessary, a selectably engageable braking mechanism to prevent movement of the undercarriage...http://www.google.de/patents/US5503416?utm_source=gb-gplus-sharePatent US5503416 - Undercarriage for X-ray diagnostic equipment
