Lessons in frustration 2 :

Accelerator cable gland in the Citroën CX 2200 saloon

In motor cars without fuel injection the accelerator pedal is usually connected to the carburettor by a Bowden cable - just like a bicycle's brake cable only more rugged. The cable passes through a hole in the sheet metal bulkhead between passenger space and engine compartment, and requires some form of a seal between cable and hole edge in order to :

• protect passengers from dust, noise, fumes and possibly fire under the bonnet,
• permit the cable sheath to move axially through the hole as its core tightens and relaxes slightly during operation,
• prevent the cable from bending excessively or from abrading on the edge of the hole in the sheet metal, and
• carry out these duties indefinitely.

Citroën solve this sealing problem by using a gland as follows. A circular hole with two lobes (i) is cut (how?) in the sheet metal bulkhead. The cable is free to slide through a close-fitting plastic gland cylinder, shown in section (ii), in which there are no sharp corners on which the cable might chafe. The cylinder is equipped with couple of lugs that match the hole's lobes.

Assembly commences by poking the cable and gland cylinder through the bulkhead hole from the engine compartment, as shown at (iii) - the cable being omitted from this sketch for clarity. Once through the hole, the cylinder is rotated through 90deg to prevent it falling back into the engine compartment. A circular plastic collar equipped with a couple of fingers (iv), is then slipped over the cylinder with the fingers protruding through the hole lobes thus preventing the cylinder from accidentally rotating and coming out if the bulkhead hole (v).

Unwanted disengagement of the collar by vibration is avoided by a compression spring forcing it up against the bulkhead (vi), the spring reacting against a thrust washer (green) retained by a circlip (black) which engages with a groove around the outside of the cylinder.

Citroën's solution certainly works, but has a couple of serious drawbacks :

• There are five gland components which have to be sourced individually and assembled on the cable for sale as a unit - a costly exercise, given the gland's mundane duty.
• Without special tools, assembly into the bulkhead is an exercise in frustration, as :
  • The operator cannot bring both hands to bear on the assembly because the space adjacent to the hole is severely constricted by other features such as the wheel arch.
  • Compressing the spring and collar prior to fitting the circlip into its groove is very difficult due to the spring's appreciable stiffness and the lack of anything for the operator to react against. (It's a bit like trying to pump up a bicycle tyre using only one hand on the pump - try it sometime!)

The conclusion reached by one bruised and extremely frustrated installer was that this solution is far too complicated for the problem posed, though admittedly something more elaborate than a blob of BluTack is necessary. Little if any thought had been given to the wishlist of non-specialist folk engaged in maintenance, an accusation which has been leveled at Citroën in the past.
But of course Citroën cars have other attractions !