covers the plumbing described hereinafter in detail the hinges between integral panels 9 10 and 11 and between the sides 12 the flaps 13 and 14 and the panels are defined by v shaped grooves in the plastic panels the same effect can be achieved by using separate panels sides and flaps and hinges between such elements horizontal slots 18 are provided near the front ends of the sides 12 for receiving a lap restraining or seat belt not shown arcuate notches 19 in the rear ends of the sides 12 are intended to receive a hip restraining belt the back 8 of the chair 3 is generally u shaped with a pair of flaps 20 defining hinges connecting the back to the seat 9 aluminum rivets not shown connect the flaps 20 to the seat 9 of the chair a flexible back support 21 extends between slots 22 in the arms of the back 8 other slots 23 are provided in such arms for receiving a chest restraining belt not shown which holds the user in the chair 3 a lug 24 extends outwardly from each side of the back 8 for connecting the back to a side 12 for such purpose a slot 25 is provided in each side near the rear end thereof when the sides 12 are folded from the flat position fig1 they are first moved beyond the vertical so that the back 8 can be inserted therebetween and then the sides 12 are moved against the side edges of the back 8 so that the lugs 24 pass through the slots 25 a rod 26 fig5 is inserted through the rear end of the side 12 and aligned holes in the lug 24 and in the side 12 into a slot.