Portable or movable railing systems are designed and used to prevent people or objects from falling off surfaces not provided with permanent barriers at the edge thereof.  Such railing systems are particularly useful if they are easy and quick to set up and take down. 
Portable railing systems are widely used in the construction industry, typically consisting of a plurality of vertical supports and horizontal rails.  The vertical supports usually have a clamp-like base.  The clamp-like base serves to secure the vertical supports at the edge of platforms, framing or flooring surfaces and usually is adjustable to fit platforms of varying thickness.  The vertical supports typically carry one or more means for supporting the rope, elongated wooden members, metal tubes or the like used to form the rails. 
U.S. Pat.  No.  3,084,759 (to Squire) discloses a guard rail support including a stanchion, a clamping means for gripping a platform and guard rail structures.  The clamping means includes a spoked nut carried by a threaded member and the clamping action is achieved by turning the spoked nut.  The guard rail structures include rectangular bands for holding rails, the bands being supported by the stanchion.  The rectangular bands are provided with screws having angularly offset handles.  When tightened, the inner ends of the screws push the rails against the inner surface of the bands. 
While the Squire patent represents an improvement in the art of securing a stanchion to floor structures or the like, and securing guard rails to a stanchion, it does not make securing and removing both stanchions and railings as quick and easy as possible.  For example, a user, typically with a number of units to erect, must tighten and loosen each spoked nut and each screw, a time consuming and fatiguing process. 
There are other problems associated with the Squire guard rail support.  The handles of the screws used to secure the rails protrude from the rectangular bands and unintentional contact with these handles can cause personal injury, equipment damage or loosen the grip of the screw end against the rail.  Another problem is that the screws will damage and split wooden rails, weakening the guard rail, reducing the number of times the rails can be reused and increasing costs.  Further, the Squire device does not have a locking mechanism to insure the spoked nut does not loosen as the result of external forces such as vibrations or being hit by an object. 
The clamping means disclosed in U.S. Pat.  Nos.  4,669,577 (to Werner) and 3,756,568 (to Mocny et al.)  are somewhat similar to the Squire clamp means in that they include a jack screw assembly, including a threaded rod and a winged nut operably coupled to the rod.  Rotation of the winged nut causes the rod to travel up or down carrying clamping surfaces toward or away from a platform.  Rails are inserted into square tubes (Werner patent) or brackets (Mocny et al.  patent) carried by uprights and secured therein by nails, screws or the like.  None of the Squire, Werner or Mocny et al.  patents discloses structure for preventing the unwanted or accidental turning of the winged nut. 
U.S. Pat.  No.  3,747,898 (to Warren) discloses a guard rail post apparatus including a post, clamping system and rail brackets.  The clamping system has a fixed jaw and a movable jaw pinned to a lever member pinned or fulcrummed to the post.  The gap between the jaws can be adjusted by selectively repositioning the lever member relative to the post and tightening a threaded driving member carried by the lever member against the post.  Rails laid in the rail brackets are secured therein by driving nails into the rails through holes in the brackets.  U.S. Pat.  No.  3,480,257 (to Bourn et al.)  discloses a somewhat similar arrangement. 
In the Warren and Bourn et al.  designs, in order to adjust the gap between the jaws a pin must be removed, then the lever member is moved to an alternative position on the post and repinned.  This is time consuming and if the pin is misplaced or dropped and not recovered the guard rail post is unworkable.  Further, the Warren patent does not disclose a rail bracket to which rails can be secured and removed quickly and easily. 
U.S. Pat.  No.  3,938,619 (to Kurabayashi et al.)  discloses a stanchion or supporting post for use with railing systems.  The stanchion includes a clamp-type base, and is telescopically adjustable for setting the general distance between the upper and lower parts of the clamping means.  To complete the tight mounting of the stanchion, a tool is required to turn a bolt. 
U.S. Pat.  No.  2,905,445 (to Blum) discloses a clamping means for mounting rails to wall brackets or posts wherein a rail is secured to the clamping means by drawing an outer cylindrical member towards an inner cylindrical member by tightening a screw that passes through the cylindrical members.  Although the Blum patent represents an improvement in the art of securing rails to vertical supports, it does not adequately address the need to secure rails quickly and easily, and a tool is required to ensure the clamp is tightened adequately. 
While the above-cited prior art discloses adaptations in portable railing systems that improve stability and make the components easier to set up and take down, one inadequately addressed problem is that it is time consuming to screw or nail each rail in or against a bracket or the like.  It would be advantageous if rails could be secured in and removed easily and quickly from a bracket in one simple operation and without using tools.  A related problem is that the rails are damaged by prior art railing systems, diminishing the safety of the railing system and increasing costs. 
The prior art clamps for securing a vertical support to platform, framing or flooring surfaces are designed with tightening mechanisms, such as wing nuts, threaded screws or threaded bolts, that carry or force clamping surfaces toward each other.  Such tightening mechanisms present at least two disadvantages.  First, it is difficult to apply sufficient torque to obtain adequate clamping force without using a tool.  Even if wings or extensions (e.g., on a nut) are provided, the length of such extensions is limited because the extensions must clear adjoining structures and, because the length is limited, an individual installing the device will be unable to exert sufficient torque to ensure a secure hold without using a tool. 
Second, in railing systems that have clamps with tightening mechanisms with extensions to assist a user in tightening the clamp, clothing or equipment may be snagged on the extensions.  Such contact could injure a person or damage equipment.  Equally serious is the possibility that the tightness of the clamp and the integrity of the railing could be compromised.  It would be advantageous to have a clamp tightening mechanism that produces sufficient clamping force with relatively little effort, yet has no exposed extensions when clamped in place.  Ideally, such a tightening mechanism would be resistant to vibration and accidental blows. 
Another problem in the prior art is that the clamp adjustment structures and methods used to vary the gross distance between two platform gripping surfaces involve removing and replacing a pin.  In addition to the time required to perform this operation and the need to use tools to remove pins, cotter keys or the like, the pins themselves could be misplaced, making the unit inoperable.  It would be advantageous to be able to adjust the distance between clamp components or gripping surfaces without disassembly and without using tools. 
Clearly, there is a need for an efficient, portable railing system that can be erected quickly and easily, maximizes safety, and complements portable staging platforms and the like.