A system comprising: a shaft having a first end and a second end, the shaft including a bore that extends through the shaft from the first end to the second end; a first shaft cap (822, 824, 840, 840') positioned on the first end of the shaft, wherein the first shaft cap (822, 824, 840, 840') includes a first collar (828, 844) having a size that is larger than the bore, and a first anchor (832, 848, 856); a second shaft cap (822, 824, 840, 840') positioned on the second end of the shaft, wherein the second shaft cap (822, 824, 840, 840') includes a second collar (828, 844) having a size that is larger than the bore, and a second anchor (832, 848, 856); a biasing mechanism arranged inside the bore of the shaft and coupled to the first anchor (832, 848, 856) of the first shaft cap (822, 824, 840, 840') and to the second anchor (832, 848, 856) of the second shaft cap so that the biasing mechanism exerts inward forces on the first and second shaft caps (822, 824, 840, 840'); characterized in that the first shaft cap (822, 824, 840, 840') includes a first keyed end (830, 846), and the second shaft cap (822, 824, 840, 840') includes a second keyed end (830, 846); the first and second keyed ends (830, 846) are configured to be coupled to a housing so that the first and second shaft caps (822, 824, 840, 840') do not rotate with respect to the housing; the shaft is configured to rotate with respect to the first and second shaft caps (822, 824, 840, 840') such that, when the first and second keyed ends (830, 846) are coupled to the housing, the shaft is capable of rotating with respect to the housing; and at least one of the first anchor (832, 848, 856) and the second anchor (832, 848, 856) is configured to swivel. a shaft having a first end and a second end, the shaft including a bore that extends through the shaft from the first end to the second end; a first shaft cap (822, 824, 840, 840') positioned on the first end of the shaft, wherein the first shaft cap (822, 824, 840, 840') includes a first collar (828, 844) having a size that is larger than the bore, and a first anchor (832, 848, 856); a second shaft cap (822, 824, 840, 840') positioned on the second end of the shaft, wherein the second shaft cap (822, 824, 840, 840') includes a second collar (828, 844) having a size that is larger than the bore, and a second anchor (832, 848, 856); a biasing mechanism arranged inside the bore of the shaft and coupled to the first anchor (832, 848, 856) of the first shaft cap (822, 824, 840, 840') and to the second anchor (832, 848, 856) of the second shaft cap so that the biasing mechanism exerts inward forces on the first and second shaft caps (822, 824, 840, 840'); characterized in that the first shaft cap (822, 824, 840, 840') includes a first keyed end (830, 846), and the second shaft cap (822, 824, 840, 840') includes a second keyed end (830, 846); the first and second keyed ends (830, 846) are configured to be coupled to a housing so that the first and second shaft caps (822, 824, 840, 840') do not rotate with respect to the housing; the shaft is configured to rotate with respect to the first and second shaft caps (822, 824, 840, 840') such that, when the first and second keyed ends (830, 846) are coupled to the housing, the shaft is capable of rotating with respect to the housing; and at least one of the first anchor (832, 848, 856) and the second anchor (832, 848, 856) is configured to swivel.